Ml400 epc light
 

Hi, I have a w163 ml 400 cdi, I am getting the epc light on the dash with reduced power, this only happens on start up after shutting down, it does not always come on but 8 times out of 10 it does, it will not go away unless I clear the stored fault code while the engine is running, I can then use the car without problem or without the epc light, it drove 300 miles no problem, turn engine off and it logs a code and epc light on restart.

The code it logs is p2020 rail pressure afterunning test quantity control valve.

Can anyone advise if they have seen this before or have any advice, I don't want to change the qcv if it's not likely to be that and could just be fuel filter or something, i have twice seen 1 air bubble in the clear pipe from filter to pump, i wondered if the pressure would be dropping off too quickly after shutdown? To add, the epc light never comes on whilst driving, the code is logged when I turn the engine off.


I look forward to any replies, thanks all

Here are the instructions to remove the valve.