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Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c - Fixed #

Posted by Simon Forsey on July 5, 2012, 10:17 pm

Year of Manufacture *: 2001
Engine Size and Code *: 2.0
( Optional ) Scanner Used: Autodiagnos
( Optional) Fault Codes: P201c

Can anyone help with an accurate description on this fault code?

I get various explanations
Autodiagnos: P201C self adaptation of mixture formation (fuel trim) mixture too rich at part load
Hanatech: P201C Injector circuit
OBD: P0172 System too rich (Bank 1)
Autodata: P201C intake manifold air control actuator bank 2 supply voltage low.

The customers complaint is the EML is on.
STFT @ idle 5% LTFT @ idle 19.5%
STFT @ 2000 rpm 17% LTFT @ 2000 rpm 19.5%

The codes suggest a rich mixture but the fuel trims suggest opposit.

The car has already been fitted with a guenuine wide band O2 sensor.

Vac is good checked at the throttle body, however if I block the intake off at the AFM the engine will continue to run which points towards a breather issue. Do these suffer from any issues with the breathers?

I cant find alot of info on this engine with a compressor and I have not had much to do with them.

Any help will prevent earley onset grey hair!

Regards

Simon

Re: Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #

Posted by Simon Kefford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3159' width='330' height='300' border=0 style='border:none;'> on July 17, 2012, 6:17 pm, in reply to "Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #"
Simon Kefford

Hi Simon

Correct definition - p201c- self adaptation rich at part load
This code is for a air leak really so smoke it if you can.
Its compensating for an air leak somewhere?

There are also several service campaigns for that car.
The latest one deals with OIL thru-out the engine wiring harness. I would look closely at that possibility.
Especially at the cam adjusters. Cam phasing could cause and air/fuel fault.

Simon

Re: Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #

Posted by Simon Kefford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3159' width='330' height='300' border=0 style='border:none;'> on July 17, 2012, 6:26 pm, in reply to "Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #"
Simon Kefford

Hi again just remembered we did one a while ago and it was a split hose underneath the intake manifold. From crankcase to intake after the MAF. It may even be covered by a recall.

Simon

Re: Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #

Posted by Milan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat5374' width='330' height='300' border=0 style='border:none;'> on July 18, 2012, 9:07 pm, in reply to "Re: Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #"
Milan Lazarevic

Very common fault breather pipe around inlet manifold, dealers keeps loads of them in stock..

Milan

Fixed #

Posted by Simon Forsey on August 1, 2012, 10:49 am, in reply to "Re: Mercedes C200 Compressor 2.0 2001 - MIL on, code P201c #"
Message modified by board administrator August 2, 2012, 4:07 pm

Hi Simon

Sorry for taking time to get back on this one.

We found the split pipe behind the super charger and I expected that to be that! However, the fuel trims were still at +22. I tried resetting the ECU with two scan tools but nothing would bring them down.

The car went into a garage that specialises in Mercs and they just turned of the check light at the ECU saying ' the check light is over sensitive on these vehicles' [we dont have to have engine check lights here in New Zealand]

When the car came back we re checked the fuel trims and they were still at +22.

I am not happy with this 'fix' and have never heard of this issue with the check light. Maybe someone could enlighten me? We will be going back to the garage, I would just like some more amo.

Regards

Simon

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