EGR content
Check the flap in the EGR valve.Check whether the proportional valve is leaking.Check whether pressure can be drained via the valve block.Check the mass flow sensor.
What you'll see
No driver-visible symptom recorded.
System reaction
The engine control unit switches off the EGR system and calibration of the mass flow sensor is switched off.
Diagnostic depth
The amount of EGR gases returned is too high, the amount of EGR gases cannot be reduced to the required level.
The fault can be due to any of the following:- The flap in the EGR valve cannot be closed. - Leakage through the proportional valve.- Blockage in the valve block channel for the relief valve which drains any remaining pressure.- The mass flow indicator may be indicating too low a value, resulting in the engine control unit concluding that the engine is receiving too high an amount of EGR gases.