W204 in limp mode.

[Bighamps]

I took my car for diagnosis and the error code pointed to the EGR valve.

They fitted a new one and it went into limp mode on the way home. They have tried various things including new hoses and replacing the engine exhaust temperature sensor.

So, today I bought an ODB reader and the code was P0401 Exhaust EGR Flow Insufficient.

It’s a W204 350 CDI 2010.

Any ideas what they have missed!

 

[onefortheroad]

Common Diagnosis Mistakes
Replacing the EGR valve without checking the air passages of the intake manifold or the temperature sensor

 

[alexanderfoti]

Or checking that the maf is reporting the correct information.