Statistics of problems at 20 week scan

20-week scan - NHS

This detailed ultrasound scan, sometimes called the mid-pregnancy or anomaly scan, is usually carried out when you're between 18 and 21 weeks pregnant.

The 20-week screening scan is offered to everybody, but you do not have to have it if you do not want to.

The scan checks the physical development of your baby, although it cannot pick up every condition.

The 20-week screening scan is carried out in the same way as the 12-week scan. It produces a 2D black and white image that gives a side view of the baby. The NHS screening programme does not use 3D or colour images.

A pregnancy ultrasound scan

Credit:

Chad Ehlers / Alamy Stock Photo https://www.alamy.com/male-doctor-using-probe-during-ultrasound-test-with-fetus-on-screen-image8705406. html?pv=1&stamp=2&imageid=209BC774-F1E4-401C-B75A-44AF9D861F55&p=2430&n=0&orientation=0&pn=1&searchtype=0&IsFromSearch=1&srch=foo%3dbar%26st%3d0%26pn%3d1%26ps%3d100%26sortby%3d2%26resultview%3dsortbyPopular%26npgs%3d0%26qt%3dAMDYKF%26qt_raw%3dAMDYKF%26lic%3d3%26mr%3d0%26pr%3d0%26ot%3d0%26creative%3d%26ag%3d0%26hc%3d0%26pc%3d%26blackwhite%3d%26cutout%3d%26tbar%3d1%26et%3d0x000000000000000000000%26vp%3d0%26loc%3d0%26imgt%3d0%26dtfr%3d%26dtto%3d%26size%3d0xFF%26archive%3d1%26groupid%3d%26pseudoid%3d788068%26a%3d%26cdid%3d%26cdsrt%3d%26name%3d%26qn%3d%26apalib%3d%26apalic%3d%26lightbox%3d%26gname%3d%26gtype%3d%26xstx%3d0%26simid%3d%26saveQry%3d%26editorial%3d1%26nu%3d%26t%3d%26edoptin%3d%26customgeoip%3d%26cap%3d1%26cbstore%3d1%26vd%3d0%26lb%3d%26fi%3d2%26edrf%3d0%26ispremium%3d1%26flip%3d0%26pl%3d

The scan is a medical examination. You'll be asked to give your permission for it to be carried out.

Make sure you understand what's going to happen, and feel free to ask any questions.

What does the scan look for?

The 20-week screening scan looks in detail at the baby's bones, heart, brain, spinal cord, face, kidneys and abdomen.

It allows the sonographer to look for 11 rare conditions. The scan only looks for these conditions, and cannot find everything that might be wrong.

You can find more information on each of these conditions, including treatment options, in these leaflets from GOV.UK:

anencephaly
open spina bifida
cleft lip
diaphragmatic hernia
gastroschisis
exomphalos
serious cardiac abnormalities
bilateral renal agenesis
lethal skeletal dysplasia
Edwards' syndrome, or T18
Patau's syndrome, or T13

In most cases, the scan will show that the baby appears to be developing as expected, but sometimes the sonographer will find or suspect something different.

If there's a condition, will the scan find it?

Some conditions can be seen more clearly than others. For example, some babies have a condition called open spina bifida, which affects the spinal cord.

This can usually be seen clearly on a scan, and will be detected in around 9 out of 10 babies who have spina bifida.

Some other conditions, such as heart defects, are more difficult to see. The scan will find about half (5 out of 10) of babies who have heart defects.

Some of the conditions that can be seen on the scan, such as cleft lip, will mean the baby may need treatment or surgery after they're born.

In a small number of cases, some very serious conditions are found – for example, the baby's brain, kidneys, internal organs or bones may not have developed properly.

In some very serious, rare cases where no treatment is possible, the baby will die soon after they're born or may die during pregnancy.

What happens at the 20-week scan?

Most scans are carried out by specially trained staff called sonographers. The scan is carried out in a dimly lit room so the sonographer can get good images of the baby.

You'll be asked to lie on a couch, lower your skirt or trousers to your hips and lift your top to your chest so your abdomen is uncovered.

The sonographer or their assistant will tuck tissue paper around your clothing to protect it from the gel, which will be put on your tummy.

The sonographer then passes a handheld probe over your skin to examine the baby's body. The gel makes sure there's good contact between the probe and your skin. A black and white image of the baby will appear on the ultrasound screen.

Having the scan does not hurt, but the sonographer may need to apply slight pressure to get the best views of the baby. This might be uncomfortable.

The sonographer needs to keep the screen in a position that gives them a good view of the baby. The screen may be directly facing them, or at an angle.

Sometimes the sonographer doing the scan will need to be quiet while they concentrate on checking your baby. But they'll be able to talk to you about the pictures once they've completed the check.

The appointment for the 20-week screening scan usually takes around 30 minutes.

Sometimes it's difficult to get a good picture if the baby is lying in an awkward position or moving around a lot, or if you're above average weight or your body tissue is dense. This does not mean there's anything to worry about.

You may need to have a full bladder when you come for the appointment. The doctor or midwife looking after you will let you know before you come. If you're not sure, you can contact them and ask.

Can I find out the sex of my baby?

If you want to know your baby's sex, you should ask the sonographer at the start of the scan, so they know that they need to check.

Some hospitals may refuse to tell you sex of the baby. Speak to your sonographer or midwife to find out more.

Can my partner or a friend come to the scan with me?

Yes. The 20-week screening scan can sometimes find the baby has a health condition. You may like someone to come with you to the scan appointment.

Most hospitals do not allow children to attend scans as childcare is not usually available. Ask your hospital about this before your appointment.

Can the scan harm me or my baby?

There are no known risks to the baby or you from having an ultrasound scan, but it's important to think carefully about whether to have the scan or not.

It may provide information that may mean you have to make some important decisions. For example, you may be offered further tests that have a risk of miscarriage, and you'll need to decide whether or not to have these tests.

Do I have to have this scan?

No – it's your choice whether to have it or not. Some people want to find out if their baby has a condition, and some do not.

If you choose not to have the scan, your pregnancy care will continue as normal.

When will I get the results of the scan?

The sonographer will be able to tell you the results of the scan at the time.

What if the scan shows something?

Most scans show that the baby seems to be developing as expected.

If any condition is found or suspected, the sonographer may ask for another member of staff to look at the scan and give a second opinion.

Scans cannot find all conditions, and there's always a chance that a baby may be born with a health issue that scans could not have seen.

Will I need any further tests?

If the scan shows there might be something, you may be offered another test to find out for certain.

If you're offered further tests, you'll be given more information about the tests so you can decide whether or not you want to have them.

You'll be able to discuss this with your midwife or consultant. If necessary, you'll be referred to a specialist, possibly in another hospital.

20 Week Ultrasound (Anatomy Scan): What to Expect

Overview

What is the 20-week ultrasound?

A 20-week ultrasound, sometimes called an anatomy scan or anomaly scan, is a prenatal ultrasound performed between 18 and 22 weeks of pregnancy. It checks on the physical development of the fetus and can detect certain congenital disorders as well as major anatomical abnormalities. Your healthcare provider will use a 2D, 3D or even 4D ultrasound to take images of the fetus inside your uterus. The ultrasound technician, or sonographer, will take measurements and make sure the fetus is growing appropriately for its age. You may also learn the sex of the fetus at this appointment.

What is the 20-week anatomy scan looking for?

A 20-week ultrasound takes measurements of your fetal organs and body parts to make sure the fetus is growing appropriately. The scan also looks for signs of specific congenital disabilities or structural issues with certain organs.

Some specific parts your provider will examine are the fetal:

Heart.
Brain, neck and spine.
Kidneys and bladder.
Arms and legs.
Hands, fingers, feet and toes.
Lips, chin, nose, eyes and face.
Chest and lungs.
Stomach and intestines.

The ultrasound technician will also:

Listen to the fetal heart rate for abnormal rhythms.
Check the umbilical cord for blood flow and where it attaches to the placenta.
Look at the placenta to make sure it’s not covering your cervix (placenta previa).
Check your uterus, ovaries and cervix.
Measure the amount of amniotic fluid.

Several images are taken during this ultrasound. You will see the sonographer draw lines on the screen. This line acts as a ruler, documenting the sizes of organs and limbs. They compare these measurements against your due date. In some cases, you might hear you are measuring ahead, on track or behind your due date. If fetal measurements are within 10 to 14 days of the predicted due date, then the fetus is considered to be developing adequately. Your due date will not change unless the fetus measures outside of that time frame.

What does an ultrasound look like at 20 weeks?

It may be hard for you to identify what you’re looking at on an ultrasound. You will most likely spot the fetus's head, nose, arms and legs. Unlike your first trimester ultrasound when the fetus looked like a tiny cluster of cells, the fetus looks more like a real baby at 20 weeks. Ask your ultrasound technician if you are unsure what you are looking at. Keep in mind, your technician can’t interpret the results of the scan for you. However, if you ask what body part you’re looking at, they can usually answer.

Test Details

How do I prepare for my 20-week ultrasound?

There isn’t much to do to prepare for your appointment. This will be one of your longer appointments — around 45 minutes for just the ultrasound. If you are seeing your healthcare provider afterward, your appointment could last up to 75 minutes. Plan ahead by making any necessary arrangements for work or childcare. Some healthcare providers recommend eating or having a full bladder to make it easier to see the images and make the fetus more likely to move.

What can I expect at my 20-week ultrasound?

First, you will lie down on the exam table. Next, an ultrasonic gel is placed on your belly. Then, an ultrasound technician will move an ultrasound wand over different spots in your abdomen. They will take images and measurements of specific organs and parts by freezing the screen. You may also see them draw lines to measure the length of the fetus's limbs or the circumference of its head. This helps them evaluate the fetus's size for its gestational age. You will get to watch the fetus on a screen, one of the most exciting parts of pregnancy.

If the fetus is positioned in a way that makes it hard to take measurements, the technician might ask you to move around a little or take a drink of something sweet to make the fetus move.

Generally, your ultrasound technician will be quiet as they work. Don’t be alarmed if the conversation is minimal or if they aren't sharing results as they go. Your obstetrician will go over the results with you either immediately after the ultrasound or at a follow-up appointment in the next few days.

After all the images are taken and your ultrasound technician is happy with all the angles and measurements, you will be able to wipe the gel off your belly.

Make sure there is room on your refrigerator: Most ultrasound technicians will send you home with a few pictures as a keepsake.

Will a 20-week ultrasound tell me the sex of the fetus?

Yes, your fetus's external genitalia has developed enough to identify its sex. Depending on the position the fetus is in, your ultrasound technician may be able to see a penis or a labia. There is a slight chance that the fetus won't cooperate, and your ultrasound technician can’t get a clear picture of its genitals. If you don’t want to know the sex, speak up ahead of time so they don’t accidentally spoil the surprise. Most of the time, a prediction is made only when the technician is certain of sex.

Is a 20-week anatomy scan harmful?

No, having a 20-week ultrasound is safe. Studies have shown that ultrasound is not dangerous to you or the fetus. A 20-week prenatal ultrasound is considered medically necessary to detect potentially life-altering anomalies.

Results and Follow-Up

When will I know the results of my 20-week ultrasound?

Anatomy scans are usually a positive experience. In most cases, your healthcare provider will not find any major anomalies. Every healthcare facility has different processes, but you will likely meet with your obstetrician right after your 20-week scan. The ultrasound technician shares the images and any findings with them. Then, your obstetrician will do their own analysis before meeting with you and sharing results.

If they find something that doesn’t look right, they may recommend additional prenatal testing or treatment for a condition found during the scan. In some cases, they recommend a wait-and-see approach. This means during delivery, they will watch for signs of the suspected condition and determine treatment at that time.

What conditions can a 20-week ultrasound detect?

A 20-week ultrasound doesn’t find all congenital conditions. However, the scan can help detect several serious conditions:

Anencephaly.
Indicators for Down syndrome or trisomy 18 and trisomy 13.
Cleft lip.
Spina bifida.
Congenital heart abnormalities.
Renal agenesis (missing one or both kidneys).
Gastroschisis (issue with the intestines).
Omphalocele (type of abdominal wall issue).
Skeletal dysplasia (problems with the bones).
Diaphragmatic hernia (a hole in the diaphragm).

It’s important to note that the scan results are not a formal diagnosis of any condition. Instead, it’s usually an indicator that further tests are needed. If your healthcare provider is concerned with any scans, they will speak to you about your next steps.

Are there any conditions a 20-week ultrasound can’t identify?

While the 20-week scan can detect certain conditions, it can’t identify everything. The scan is meant to provide indicators, or markers, of serious health problems. There are some conditions you will not know about until your baby is born. For example, many heart abnormalities are not found until birth and you might not know if your baby has scoliosis.

Will I need further tests or ultrasounds?

If your healthcare provider is concerned about anything in your 20-week scan, they may recommend further tests. Some of these tests could include amniocentesis, chorionic villus sampling or additional ultrasounds with a perinatologist (physicians who specialize in high-risk pregnancies).

Speak with your healthcare provider early in your pregnancy to make sure you understand the types of noninvasive prenatal testing available to you. Several tests that indicate an increased risk for congenital anomalies can be done before 20 weeks of pregnancy.

Additional Details

What does a girl look like at a 20-week ultrasound?

One of the best ways to identify a girl on ultrasound is to look for three lines. However, it’s always best to leave the identification of sex up to experienced professionals.

What does a boy look like at a 20-week ultrasound?

Sometimes it’s the absence of the three lines that tell the ultrasound technician you have a boy in your belly. Other times you can see a protrusion coming from a round sack. This is the fetus's penis and testicles. It’s always best to let your healthcare providers determine fetal sex.

A note from Cleveland Clinic

It’s normal to be both excited and nervous about your 20-week ultrasound appointment. You will get to see the fetus and find out how it's developing. Talk to your healthcare provider about any concerns you have so they can offer reassurance and ease your worries. In most cases, the 20-week anatomy scan is a positive experience for soon-to-be parents.

Microcephaly

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Magnitude of the problem

\nMicrocephaly is a rare condition. The prevalence of microcephaly is estimated to vary considerably due to different definitions and depending on target populations. Scientists are investigating a potential, though unproven, link between an increase in microcephaly cases and Zika virus infection.

Diagnosis

\nMicrocephaly can sometimes be diagnosed by fetal ultrasound. The most appropriate period for diagnosis is the end of the second trimester (about 28 weeks) or the third trimester of pregnancy. nine0285

\nChild circumference of newborns should be measured at least 24 hours after birth and compared with WHO standard child development indicators. The results are interpreted taking into account the gestational age of the child, as well as his height and weight. If there are suspicions, the child is sent for examination to the pediatrician and for a brain scan, the circumference of his head is measured once a month in early infancy and compared with standard indicators. Doctors should also test for known causes of microcephaly. nine0285

Causes of microcephaly

\nMicrocephaly has many potential causes, but often the cause remains unknown. The most common causes include:

intrauterine infections: toxoplasmosis (caused by a parasite found in meat that has not been properly cooked), rubella, herpes, syphilis, cytomegalovirus, and HIV;
exposure to toxic chemicals: maternal exposure to heavy metals such as arsenic and mercury, alcohol, radiation, and smoking; nine0005 \n
genetic pathologies such as Down syndrome; and
severe malnutrition during fetal development. Signs and symptoms with vision. Some children with microcephaly develop quite normally. nine0285
\n

Treatment and care

\n

\nThere is no specific treatment for microcephaly. A multidisciplinary team is needed to evaluate and treat newborns and children with microcephaly. Early promotional activities and play programs can have a positive impact on development. Family counseling and parental support are also very important.

\n

WHO activities

\n

\nSince mid-2015, WHO has been working closely with the Americas to investigate and respond to the outbreak. nine0285
\n

\nThe Strategic Response Program and Joint Action Plan outlines the steps being taken by WHO and partners in response to Zika virus and potential complications:

\n
- Working closely with affected countries to conduct outbreak investigations caused by the Zika virus and responding to an unusual rise in microcephaly cases.
- Engage with local communities to communicate the risks of Zika virus disease and how they can protect themselves. nine0005 \n
- Provide advice and mitigate the potential impact on women of childbearing age and pregnant women and families affected by the Zika virus.
- Assist affected countries to improve care for pregnant women and families with children born with microcephaly.
- Investigation of reported increases in microcephaly cases and possible association with Zika virus infection, with the participation of experts and partners.
\n

","datePublished":"2018-02-16T09:06:00.0000000+00:00","image":"https://cdn.who.int/media/images/default -source/imported/measure-microcephaly475-jpg.jpg?sfvrsn=7be7eab_0","publisher":{"@type":"Organization","name":"World Health Organization: WHO","logo":{" @type":"ImageObject","url":"https://www.who.int/Images/SchemaOrg/schemaOrgLogo.jpg","width":250,"height":60}},"dateModified": "2018-02-16T09:06:00.0000000+00:00","mainEntityOfPage":"https://www. who.int/ru/news-room/fact-sheets/detail/microcephaly","@context" :"http://schema.org","@type":"Article"}; nine0285
Key Facts
- Microcephaly is a condition in which a baby is born with a small head or the head stops growing after birth.
- Microcephaly is a rare condition. One child out of several thousand children is born with microcephaly.
- The most reliable way to detect microcephaly in an infant is to measure the circumference of the infant's head 24 hours after birth, compare it with the WHO standard child development indicators, and then measure head growth in early infancy. nine0005
- Children born with microcephaly may suffer from seizures as they grow, as well as physical and learning disabilities.
- There is no specific test to detect microcephaly in a fetus, but an ultrasound scan in the third trimester of pregnancy can sometimes reveal the problem.
- There is no specific treatment for microcephaly.
Microcephaly is a neonatal malformation in which the baby's head is much smaller than other babies of the same age and sex. Combined with improper brain development, children with microcephaly may develop developmental disabilities. The severity of microcephaly varies from mild to severe. nine0285
Magnitude of the problem

Microcephaly is a rare condition. The prevalence of microcephaly is estimated to vary considerably due to different definitions and depending on target populations. Scientists are investigating a potential, though unproven, link between an increase in microcephaly cases and Zika virus infection.

Diagnostics

Microcephaly can sometimes be diagnosed with a fetal ultrasound. The most appropriate period for diagnosis is the end of the second trimester (about 28 weeks) or the third trimester of pregnancy. nine0285
Head circumference of newborns should be measured at least 24 hours after birth and compared with WHO standard child development indicators. The results are interpreted taking into account the gestational age of the child, as well as his height and weight. If there are suspicions, the child is sent for examination to the pediatrician and for a brain scan, the circumference of his head is measured once a month in early infancy and compared with standard indicators. Doctors should also test for known causes of microcephaly. nine0285
Causes of microcephaly

Microcephaly has many potential causes, but often the cause remains unknown. The most common causes include:
- intrauterine infections: toxoplasmosis (caused by a parasite found in undercooked meat), rubella, herpes, syphilis, cytomegalovirus and HIV;
- exposure to toxic chemicals: maternal exposure to heavy metals such as arsenic and mercury, alcohol, radiation and smoking; nine0005
- genetic pathologies such as Down syndrome; and
- severe malnutrition during fetal development.
Signs and symptoms

Many babies born with microcephaly may have no other symptoms at birth, but may later develop epilepsy, cerebral palsy, learning disabilities, hearing loss, and vision problems. Some children with microcephaly develop quite normally.

Treatment and care

There is no specific treatment for microcephaly. A multidisciplinary team is needed to evaluate and treat newborns and children with microcephaly. Early promotional activities and play programs can have a positive impact on development. Family counseling and parental support are also very important.

WHO activities

Since mid-2015, WHO has been working closely with the Americas to investigate and respond to the outbreak. nine0285
The Strategic Response Program and Joint Action Plan outlines steps being taken by WHO and partners in response to Zika virus and potential complications:
- Working closely with affected countries to investigate the Zika virus outbreak and respond to unusual an increase in the incidence of microcephaly.
- Engage with local communities to communicate the risks of Zika virus disease and how they can protect themselves. nine0005
- Provide advice and mitigate the potential impact on women of childbearing age and pregnant women and families affected by the Zika virus.
- Assist affected countries to improve care for pregnant women and families with children born with microcephaly.
- Investigation of reported increases in microcephaly cases and possible association with Zika virus infection, with the participation of experts and partners.
- Child growth standards
I want to know everything: what is computer diagnostics and how is it carried out? In general, everything is so. And yet we will try to tell about the process in more detail: believe me, this is a very interesting process.

What is OBD?

Let's start from the very beginning. To connect diagnostic equipment to the car, you need a special connector that all cars now have, and which is sometimes called simply OBD-II. In fact, OBD-II is not a connector, but a whole system of on-board diagnostics. And despite the fact that it firmly entered our lives only 20 years ago, its history begins back in the 50s of the last century. nine0285
In the middle of the 20th century, the American government suddenly came to the conclusion that the rapidly growing number of cars somehow had a bad effect on the environment. The government began to pretend that it wants to improve this situation at the legislative level. Automakers, in turn, began to pretend that they are complying with invented laws.

Extremely diverse diagnostic systems appeared, the task of which was limited to monitoring emissions into the atmosphere (and since there was no sophisticated equipment, the maximum that could be more or less adequately monitored was fuel consumption). No one (sometimes even the manufacturers themselves) could use such systems normally. And when, by the mid-70s, the Air Resources Board (ARB) and the Environmental Protection Agency (EPA) began to realize that nothing good could be achieved, they began to strongly recommend the introduction of new systems . nine0285
They would not just blink a light, “if something went wrong”, but would allow you to quickly check the car for compliance with environmental standards. The first manufacturer to respond was General Motors, which developed its own ALDL interface. Of course, we have not yet talked about any world standard, and about the American one too. In 1986, ALDL was modernized, but things never reached the desired scale. And only in 1991, the California Air Resources Board (California Department of Air Control) obliged all American automakers to equip their cars with the OBD-I (On-Board Diagnostic) diagnostic system, developed in 1989 year.

What could be monitored using OBD-I? Of course, the first priority was to monitor the composition of the exhaust gases. It was possible to monitor the operation of the electronic ignition system, oxygen sensors and the EGR recirculation system. In the event of a malfunction, the MIL (malfunction indicator lamp) lighted up. No more accurate information could be obtained, although over time the light bulb was taught to blink with a certain sequence, which made it possible to identify at least a faulty system. But this soon became not enough. nine0285
In January 1996, a new version of OBD-II became mandatory for all vehicles sold in America. The main difference between this diagnostic system and OBD-I was the ability to control the power supply system, and it could also be checked on the car using a plug-in scanner. This was what the police did. They didn't give a damn about anything but toxicity - after all, this whole system was originally developed to control exhaust gases. It was assumed that the diagnostic system on the new car had to work for five years or one hundred thousand kilometers. But the story of OBD-II does not end there. nine0285
In 2001, all cars sold in Europe were required to have an EOBD (European Union On-Board Diagnostic) system, now with a CAN bus (more on that some other time). In 2003, the Japanese introduced a mandatory JOBD (Japan On-Board Diagnostic), and in 2004, the presence of EOBD becomes mandatory for all diesel cars in Europe.

This is a very (too) brief history of OBD-II. I deliberately did not complicate it, you are hardly interested in reading about the recessive and dominant bits of the Controller Area Network specification? So I think that's enough to get started. Let's take a better look at the OBD-II connector "live". nine0285
Meeting place cannot be changed

I have already said that through the diagnostic connector, Californian cops, if desired, should have easily connected to the system itself. To simplify the task, it was decided to install the connector no further than 60 cm from the steering wheel (although, say, the Chinese often ignore this requirement, and sometimes Renault engineers indulge in the same). And if earlier the connector could be found even under the hood, now it is always within the reach of the driver. What is a connector? nine0285
In general, it is called DLC - Diagnostic Link Connector. It is quite obvious that the block itself also began to meet the same standard. The connector has 16 pins, eight in two rows. The standard also defines the purpose of the pins in the block. For example, pin number 16 (the rightmost in the bottom row) should be connected to the "plus" of the battery, and the fourth should be ground. And yet, six contacts are at the disposal of the manufacturer - something can be located there at his request.

You can often hear the word "protocol" from diagnosticians. In this case, this is the standard for data transfer between individual blocks of the diagnostic system. Here we are already dangerously approaching computer science, but nothing can be done: computer diagnostics. You'll have to endure a little more. nine0285
OBD-II developers have provided five different protocols. In very, very simplified terms, these are five different ways of transmitting data. For example, the SAE J 1850 protocol is used mainly by Americans, the data transfer rate for it is 41.6 Kb / s. But ISO 9141-2 is not widespread in the USA, the transfer rate here is 10.4 Kb / s. However, we do not need to know all this.

For now, just remember:

the OBD-II diagnostic connector is the same everywhere, the pinout is the same, and which connectors will be used to connect the scanner depends on the protocol used by the manufacturer. nine0285
Well, now let's try to diagnose the car - specialists from the Speed Laboratory company will help us with this. Along the way, let's see what a real diagnosis is.

What can diagnostics do?

Let's start with the fact that connecting a cheap multi-brand scanner and counting one or two errors is not even close to diagnostics. And it would be a big mistake to believe that the diagnosis is made by the scanner, and not by the person. In fact, they work in pairs, and if one of them is significantly dumber than the other, nothing good comes of it. I hate numbered lists, but I use one to more clearly show what should be included correct computer diagnostics :
1. History taking.
2. Read existing and stored errors.
3. View live data.
4. Data logging "in motion".
5. Interrogation and comparison.
6. Actuator tests.
7. Use of instrumental diagnostic methods.
A lot of things you don't understand? We will calmly reach each of the points.

There are also post-diagnostic works: adaptation, activation of additional functions... But more about that in one of the following publications. For now, let's focus on troubleshooting and go through all the steps. nine0285
History taking

Before starting work, a good diagnostician will definitely ask the owner what is wrong with the car, how the malfunction manifests itself, under what conditions, with what frequency, what preceded the appearance of the malfunction ... In a word, he will behave like an experienced doctor, moreover not from a free clinic, but from a good medical center.

Our experimental MINI is absolutely healthy, so there is nothing to ask in this case. However, sometimes it makes sense to carry out diagnostics as a preventive measure, without waiting for the Check Engine to shine constantly or wink periodically from the instrument panel. nine0285
Reading existing and saved errors

So, we connect a scanner and a laptop with software from BMW to our Minik (we won’t remind you how BMW and MINI are connected, everyone is literate here). Of course, through the diagnostic connector. By the way, Mini does not want to pass diagnostics normally on one battery, so we connect an external power source. But this is a feature of the car, the exception, not the rule. Now we are waiting for the establishment of communication with the car. We look at the picture on the laptop screen. nine0285
First of all, we can see general information about the car - from the current mileage to the engine number and gearbox. By the way, if you buy a used car, then often diagnostics will help determine its true mileage, which will also be visible, for example, in automatic transmission.

Or even more interesting: if you open the repair history, you will see at what mileage the last intervention was carried out (maybe someone threw off errors, adapted some mechanism or did something else). And if there is a mileage of 100 thousand, and only 70 on the odometer, then someone wants to deceive you. It is far from always that such an opportunity is 100%, and the “rollers” of runs are often inventive and not lazy - sometimes they clean up runs everywhere, although this is rare. nine0285
But we digress. We quickly scan for errors and in the "Error Accumulator" section we still find such entries that indicate errors in the electric power steering!

I emphasize once again: if the “check” is not lit on the machine and no obvious malfunctions appear, this does not mean that they do not exist. The electronics may not work correctly without notifying you without connecting the scanner.

Therefore, computer diagnostics, especially if you have an expensive car with complex electronics, should be carried out regularly so that many breakdowns can be preventively eliminated before they turn into something serious. nine0285
But back to our MINI. We open the EUR error record and look at the so-called Freeze Frame (frozen frame) - it describes under what conditions this error appeared. In our case, this happened once at a run of 120 thousand kilometers, at a speed of 117.5 km / h, the battery voltage was 16.86 V.

The data in the Freeze Frame helps to understand why the error occurred. Not always, of course, but any related information about speed, mileage, voltage, etc. may be important. This is all provided that the specialist knows how to think. nine0285
After all, it happens that home-grown "diagnostics" simply see which part in the car is "buggy", and immediately offer to change it in the assembly "at random" , because, they say, only the Holy Spirit knows the cause of the error, unravel it impossible. This is all from great greed and lack of professionalism. And we're moving on...

Live Data

Live Data is the data that can be obtained in real time. There are simple data - for example, engine speed or coolant temperature. nine0285
And there are some that are impossible to find out without a scanner. For example, the voltage of the pedal position sensors (we are talking about the electronic gas pedal). There are two of them, we look at the readings: 2.91 V on one and 1.37 V on the second. Now we press the pedal and look at the values: 3.59 V and 1.58 V. Actually, this is Live Data - what happens to the mechanism in real time.

The data stream can also be viewed on the go. It can be very useful to see how the on-board electronics of the car react to various manipulations, and what Live Data shows at the same time. nine0285
Interrogation and comparison

This is the work of the diagnostician, not the equipment. After the machine has been tested by all available means, the readings taken will have to be comprehended and compared. Was the voltage normal? What about resistance? What about the temperature? Well, and so on.

Actuator test

This is done to check their performance. Usually - just to make sure that the node works as expected. We go to the menu section "Activation of the part" (yes, the Russification here is somewhat strange) and start, for example, the electric fan of the cooling system. Working. What can it be useful for? Let's say the engine is overheating. If the fan had not turned on forcibly, the cause of overheating would have been revealed. nine0285
Use of additional measuring devices

It happens that diagnostics cannot show which of the system elements is out of order. Take, for example, the same “electronic gas pedal”. Let's say the voltage is abnormal. The scanner will show this, we have already seen this. But what is the reason for the voltage drop?

Here, only measuring the resistance of the rheostat with an ohmmeter and visually inspecting the tracks for damage or worn contacts will help. Or another example. Diagnostics shows errors on the crankshaft and camshaft position sensors. Most likely, this indicates a shift in the timing phases, that is, a chain stretch. How phase shifted? Only an oscilloscope can help with this. Still, replacing the timing chain is an extremely expensive job, especially on some kind of V8. It's better to know for sure. nine0285
One oscilloscope can also be indispensable. For example, this can also include pressure testing of the intake with a smoke machine, and a test of the performance of injectors “with a return”, and control of the same diesel injectors on a special injector stand, and much more ...

You can also apply diagnostic measurements on a dyno few people use it due to the lack of equipment. After all, measuring on the stand allows you not only to see the numbers of power and torque, but also to look at the nature of the curve of both and simultaneously take data on boost pressure, AFR, exhaust gas temperature, torque distribution along the axles and wheels, and much more. But this is exotic in Russia. nine0285
Therefore, we note this item separately: a real diagnostician does not disdain to get his clothes dirty, because at the stage of instrumental diagnostics, you will have to open the hood, climb into the wiring, dismantle problem sensors or components and check their condition visually and for correct functioning, ring the wiring, connect an oscilloscope, multimeter and other necessary devices. Computer diagnostics involves the use of not only one scanner (and in real life there should be more scanners - more on that in a separate article), but also other diagnostic tools. nine0285
Logging

It is used in a case that would definitely baffle me: if the error has a floating character. Just the situation when the service usually says: “well, now everything is working, but as soon as it happens again, come.” Indeed, such a malfunction can be difficult to determine. But there is a way out.

A special scanner is connected to the diagnostic connector (usually a mini-scanner that is simply inserted into the OBDII connector and does not hang, does not dangle, works autonomously, does not interfere with the driver. In general, it does not require any participation of an ordinary user - a car service client) and send the client to ride according to their needs. nine0285
In the meantime, the scanner is working hard, writing a log, and at the moment the problem occurs, it additionally registers the error itself and the conditions for its manifestation. The method is convenient, and most importantly, practically indispensable in the presence of complex "floating" errors. And another advantage is that the specialist does not have to sit in real time and monitor everything that is happening in the car. Sometimes it is simply impossible, and if possible, it is very difficult. It is much more convenient then just to pick up all the records and sit thoughtfully over the logs. nine0285
And in the end I will say…

All of the above is just the tip of the iceberg. We will gradually raise the entire block, but not immediately.

For example, we did not say anything about codes, although this topic is very interesting. Many have probably heard something like this: “I have a code P0123. What does it mean?". Yes, you can see. This is the Throttle Position Sensor 'A' output high. In short, all errors are divided into groups. P - engine and transmission, B - body, C - chassis. nine0285
There are also divisions inside. It’s not necessary to list everything for a long time, but at least for an example: P01XX - mixture control system, P03XX - ignition system and misfire control system, but from P07XX to P09XX - transmission. Subsystems are indicated instead of XX. For example, P0112 is a low intake air temperature sensor, and P0749 is a pressure control solenoid valve error. There are hundreds of codes, but an ignorant person will not get anything sensible from this information. nine0285
In general, of course, this is an important question: let's say you have made a diagnosis somewhere, but what to do next? In this case, you can once again check the qualifications of specialists. It is almost always possible to understand the origins of the appearance of a particular error. So if you hear advice to change parts one by one until the car runs fine, get your feet out of such a service. You can understand them: changing parts sold at a premium is much easier than studying to be a diagnostician and poking around in little things that will not bring a lot of money. nine0285
Official dealers are especially cynical in these matters. And if the work is done under warranty, then the path will be so. But if you have to change the shutter at your own expense, then it can be oh, how expensive.
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