Information on diagnostics

Troubleshooting in exhaust gas recirculation system on Otto and diesel engines (2)

Tips for troubleshooting

Irregular idling? Is the engine jerking when starting up the vehicle or when driving? Lack of power? Dirty EGR valve? Diagnostic trouble code P0102, P0103, P0401 or P0402 in the fault code memory?
The problem may be in the EGR system.
We explain possible causes and how to remedy them.

Whether dealing with pneumatic EGR valves or an electro-pneumatic pressure transducer, as in this case: The function can easily be tested using a vacuum hand pump.

Salt and dirt may damage the sensor of an air mass sensor – they will at least falsify the measurements, which in turn could aff ect exhaust gas recirculation.

Since EGR valves do not soot themselves, it is essential to search for the causes of soot formation.

The most common cause for malfunctions in the EGR system are stuck or carbonised EGR valves. Besides gaseous pollutants, recirculated exhaust gas also contains soot particulates, in particular in the case of diesel vehicles.
Due to oil in the intake air, carbon deposits or carbon fouling are caused which eventually the force of the valve can no longer cope with ñ the EGR valve can then no longer open, or it remains in its open position. This results in jerking, irregular idling or insuffi cient engine power.

The causes of a high portion of oil in the intake or charge air may be malfunctions in the crankcase ventilation, worn bearings, a clogged oil return line on the turbocharger, worn valve stem seals or guides, the use of unsuitable engine oil qualities or an excessive engine oil level.
Exceptionnally intense deposits may also be caused by faults in the injection system.

Though EGR valves are designed for the high temperatures in the exhaust branch system, heat damage to the valve may occasionally occur. Such damage can be caused by incorrect actuation, excessively high exhaust gas back pressure or a blow-off valve ("waste-gate valve") of the turbocharger which does not open. There may even be some manipulation ("tuning") to increase the boost pressure.

On pneumatic EGR valves, one potential cause of malfunctions can be found in the entire section of vacuum control (vacuum pump, vacuum lines, solenoid valves).

Electric EGR valves and solenoid valves can mostly be actuated by way of an actuator diagnosis by the engine tester. The switching of a functioning valve can easily be heard when the engine is at a standstill.

Whenever a new EGR valve is installed after a defect, and the vehicle behaves as if the valve had not have been replaced at all, the map data required for operation must fi rst be "re-learnt".
This is achieved either in the course of a longer test drive or by using a specifi c program option in the engine tester, e.g. "Basic settings".

We strongly advise against cleaning the EGR components! If a component really is already defective, no
improvement will be achieved by cleaning it. And if functioning components are treated in this way, they may be damaged as a result of cleaning.
A defective component should always be replaced by a new one.

Since EGR valves do not soot themselves, it is essential to search for the causes of soot formation.

Salt and dirt may damage the sensor of an air mass sensor – they will at least falsify the measurements, which in turn could aff ect exhaust gas recirculation.

Whether dealing with pneumatic EGR valves or an electro-pneumatic pressure transducer, as in this case: The function can easily be tested using a vacuum hand pump.

Further information on troubleshooting in the exhaust gas recirculation, complaints, possible causes and remedies is available here.

download

This might also interest you

Use of cookies and data protection

Motorservice Group uses cookies saved to your device in order to optimize and continuously improve its websites, as well as for statistical purposes. Further information on our use of cookies can be found here, together with our publication details and data protection notice.

By clicking on “OK” you confirm that you have taken note of the information on cookies, the data protection declaration and the publication details. You can also change your cookie settings for this website at any time.

Privacy settings

We place great importance on transparent information relating to all aspects of data protection. Our website contains detailed information on the settings you can select and what effect these settings have. You can change your selected settings at any time. Regardless of the selection you choose, we will not draw any conclusions regarding you as a person (except where you have explicitly entered your details). For information on deleting the cookies, please see the help function in your browser. You can find out more in the data protection declaration.

Change your privacy settings by clicking on the corresponding buttons

Necessary

Cookies essential for the system ensure that the website works correctly. Without these cookies, malfunctions or error messages may occur.

This website will:

  • Store cookies required by the system
  • Store the settings you make on this website

This site wil never do the following without your agreement:

  • Store your settings, such as the language selection or cookie banner, so that you do not have to repeat them in the future.
  • Evaluate visits anonymously and draw conclusions to help us to optimize our website.
  • Draw conclusions regarding you as a person (except where you have explicitly entered your details, e.g. in contact forms)

Convenience

These cookies make the website easier to use and save settings, for example, so that you do not have to repeat them every time you visit the site.

This website will:

  • Store cookies required by the system
  • Store your settings, such as the language selection or cookie banner, so that you do not have to repeat them in the future.

This site wil never do the following without your agreement:

  • Evaluate visits anonymously and draw conclusions to help us to optimize our website.
  • Draw conclusions regarding you as a person (except where you have explicitly entered your details, e.g. in contact forms)

Statistics

Statistics cookies enable us to evaluate the usage behaviour on the website anonymously – without enabling any conclusions to be drawn about you as a person. This enables us to measure the performance of the website and to improve it continuously to offer a better user experience.

This website will:

  • Store cookies required by the system
  • Draw conclusions regarding you as a person (except where you have explicitly entered your details, e.g. in contact forms)
  • Evaluate visits anonymously and draw conclusions to help us to optimize our website.

This site wil never do the following without your agreement:

  • Draw conclusions regarding you as a person (except where you have explicitly entered your details, e.g. in contact forms)

Of course, we will always respect the do-not-track (DNT) setting in your browser. In this case, no tracking cookies are set and no tracking functions are loaded.