EGR Valve?

EGR Valve Can Block Or Fail An Cause Running Faults but what do they actaully do ?

EGR valve (Exhaust Gas Re circulation) directs a small amount of exhaust gases back into the inlet air charge, and this lowers the maximum temperature of the burning fuel.

The valve ensures the EGR system is disabled/ closed at idle, when it would otherwise lead to erratic idling, and at peak power, when adding exhaust
gases would reduce power output and create a boost leak.

Because exhaust gases are pumped into the engine this valve is very likely to clog up and stick and become coked up on some applications and start to malfunction intermittently and then permanently.


This can have a significant effect on the performance of the turbocharger as its trying to compensate for boost leaking past what should be a closed valve…this in turn causes the turbo to over speed which you can read about in one of our other sections on route causes for turbo failure. It is important to check the valve is functioning correctly.

So what will happen if my EGR valve becomes faulty ?

A faulty EGR  can result in excessive carbon/soot at the turbine end of the turbo charger. This could cause the VNT mechanism to become clogged and stick which in many cases will cause engine management lights to appears along with reduced performance known as “limp mode”.

EGR Valve
EGR Valve

Excessive production of nitrogen oxide

Smoking at idle and low rpm

Erratic idling or unable to idle

Poor operation when cold

Increased fuel consumption

Lack of performance

Fault light and/or fault code activated

Possible reasons why the Valve does not open

EGR  sticks/gummed up

Air leak on the vacuum side

Vacuum connections disconnected leaking or incorrect

Faulty electric switch pressure converter valve Non-opening blow-off valve (dump vale)
(for turbocharger).

Possible reasons why the Valve does not close

Heavy carbon deposits on egr tappet or valve

EGR valve damaged through overheating due to:

Incorrect control of egr

High exhaust back pressure – Blocked dpf or cat or collapsed exhaust baffles

Failed dump valve

Air flow meter or other sensor signal faulty

Intake pipe in the EGR system partly constricted by deposits or blocked

Oil leak from turbocharger causing carbon build up – please see blocked dpf