Jaxo

Hi
My MB C200 Kompressor 2007 started with performance problems.
Low power and cannot accelerate. Then the "check engine" light went on.
I plugged it in on my Scan-tool.
It reported:
Stored: error P0171 - System too lean
Pending: error P0171 - System too lean
Pending: error P0130 - O2 Sensor Circuit

I cleared the errors and the car was going smooth again.
Bought a new OEM fuel filter. For me the same symptoms as
a dirt fuel filter. Never installed it, because the car was running fine.

Now after about 1 month the same problem. I checked with Scan-tool
and it reported:
Stored: Error P0172 - System too Rich
Pending: Error P0410 - Secondary Air Injection System

So I cleared the errors and no improvement.

I wanted to change the fuel filter and cannot find it where it
should be. One guy told me it is part of one of the 2 fuel pumps
inside the tank; right hand-side pump.

Could it be the Mass Airfow Meter or something else.
I took a torch and looked inside the tank. It looks clean and
I do not see any filter.

Please advise.

Thanks.
Jaxo

Glyn M Ruck

The filter is built into the tank sender unit that contains the fuel pump on newer W203's.

Clean the MAF
Check that you have > 3.8 bar or 55psi fuel pressure at the Schrader valve on the rail while cranking.
Check for a vacuum leak.
Your upstream O2 sensor is suspect.

Good luck!

Jaxo

Do they ever change this filter when its going for a service?
Where can I find a workshop manual and that O2 sensor location?

johnand

That filter has a 10year/143K mile change interval.

Jaxo

I went for another drive today, and the scantool gave me error P0299 - Supercharger Underboost.

Glyn M Ruck

Underboost & lean makes no sense unless the wastegate is being opened in an attempt to richen mixture.

O2 sensor:

Jaxo

I had a look at the MAF. Not easy to remove the bottom screw and getting it back
into place...... What's the best way to clean it?

I unpluged the MAF and went for a ride. Same as with it connected.
Maybe a little different.

And how do I test the O2 sensor and/or clean it?
My nearest dealer is 200km away - small town.
Will ask around for someone to test the pump. They say it can only be the right
hand side pump... why?

Glyn M Ruck

Clean the MAF with CRC MAF cleaner.

When you unplug the MAF you force the ECU onto a default mixture MAP.

You need to replace the upstream O2 sensor.

There is only one fuel pump. The other side is just a level sensor.

Jaxo

I received this O2 error this morning when using a different program.
Will buy a new one and install.

I also cleaned the little filter at the bottom of the right hand side fuel pump.

Jaxo

Removing and cleaning the fuel pump filter photos.

I took the car to a mech and on our 2nd test drive the inter-cooler
pipe came off. Waiting for his verdict.....