We have a G400 Cdi, which has an intermittent problem whereby the engine will die suddenly with the message EPC (electronic power control: visit workshop...). This is a dangerous situation as when it happens there is no warning and there is complete loss of power, including steering etc.
Usually, this happens within the first 10 minutes of driving the car and it can sometimes take up to 12 hours before it will restart. In this case, the engine will normally fire up and will then turn off within 3 seconds with the EPC message.
Carsoft diagnostics had revealed DTC errors P2024 and P2001. The first was related to the exhaust gas recirculation valves, one of which we found to be stuck. However, after cleaning them the remaining fault is P2001, which still happens intermitently with the engine dying and the EPC message in the dash.
As mentioned, it seems that the problem occurs usually within the 1st 10 minutes of driving with the following cicumstances:
1.) Mostly, but not always, when driving down hill or with trailing throttle, or sometimes in reverse.
2.)It can take between 1 minute and 12 hours to be able to sucessfully restart the engine. (Engine actulally will restart fine, but only runs for 3 secs before EPC message and P2001 fault indicated.)
3.) After such an occurrance, if the car is used every day, then the fault is much less likely to happen again, until the car is not used for a day or two.
What we have done so far:
a.) replaced all fuel filters
b.) replaced acellerator pedal-position potentiometer.
c.) Checked all other systems (fuel-pressure regulators, sensors etc.)
d.) Checked wiring to ECU etc
e.) Checked and replaced all relevant fuses, swapped relays etc.
f.) Air mass flow sensors were replaced earlier.
Now, it seems that according to the MB DTC codes the following could be relevant to the P2001 error:
P2001 check N3/9 (controller CDI) A/D converter.
P2001 check N3/9 (controller CDI) reference voltage
P2001 check N3/9 (controller CDI) voltage supply 1.
P2001 check N3/9 (controller CDI) voltage supply 2.
P2001 check N3/9 (controller CDI).Circuit voltage supply unit fault
P2001 Component N15/3 (ETC control module) is faulty.
P2001 Malfunction of exhaust gas recirculation (functional chain)(P0400)
P2001 N3/9 (controller CDI) reset identification error
P2001-001 M16/6 (throttle valve regulation part),throttle valve position reliability [P0638]
P2001-002 M16/6 (throttle valve regulation part),PWM-signal:limit 2[P0638]
P2001-004 M16/6 (throttle valve regulation part),PWM-signal interrupt [P0638]
P2001-008 M16/6 (throttle valve regulation part),PWM-signal:limit 1
My question is:
My next point of investigation would be the Throttle regulation valve. But, my main question is does anyone here know whether this would be likely to cause the engine to die completely as it does?
I was wondering whether the problem might be a wiring fault or a faulty ECU, but after many months, the fault does seem to be following a pattern, which would probably be more random and less defined with something like a broken wire or broken track in the ECU printed-circuit boards.