High CO and warnings in Mercedes 200E Kompressor (W211)

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Romeo57

New Member
Joined
Mar 14, 2019
Messages
1
Location
Sweden
Car
Mercedes 200E Kompressor
Hi, my name is Gunnar Lindqvist, I have big issues with my Mercedes, a W211 200E Kompressor 2004. I will try to give as much information as possible and hope that someone can give me hints to similar problems. The car has been at the car inspection with no pass due to high CO. Follows the diferent values. Limit value in Sweden inside brackets: C= 1,3 (0,3), CO 2500 rpm = 1,3 (0,2), HC = 246 (200), Lambda = 0,96 (0,97-1,03). There were also fault codes, and warning lamp on.
I left the car at a workshop with good reputation. They kept the car for 4 weeks but they did not manage to get rid of the fault codes. I booked a meeting with Philipssons, the great Mercedes import and workshop in Sweden (Malmö), they charged 2000 sek (200 eur) to make an analysis, and gave me the diagnose that the solenoid valves were leaking oil and needed to be replaced. The sockets were of course contaminated with oil and must be cleaned. The cost would be 11000 sek (1100eur) plus the cost for analysis, and they couldn't say this was the complete cause. I decided to take back the car, and paid the 2000 sek for analysis, as was already in a deal. Besides this information was already known for me from the first workshop visit.
I decided to try myself, since I am a technician and did a lot of mechanichal work with cars when I was young, considering cars were less complicated in the seventies. I bought a Carsoft code reader, I bought new solenoid magnets, and I replaced them and cleaned up oil contamination inside the sockets. Before replacement I had 6 fault codes, but today after replacement I have 4. Those are: P200A-002 and P200-004, both of them related to B2/5 (Hot film MAF sensor), P2038-004 G 3/1 (O2 sensor downstreamm TWC) open Circuit and finally P2029-002 Selfadaption of mixture formation at lean stop (Tendency of Engine towards rich. After zeroset the lamp I can drive easily 100 km without the lamp start to light, but as far as I stop and do next Cold start it light up again.
Trying to logic out the fault codes, it seems that they point on the downstream lambda and also the air mass airflow meter. I inspected the lambda DS last Saturday end, and I had some oil contamination inside the socket of the lambda. I cleaned as good as possible. In the evening I googled internet and found a 9 years old thread with a persón who had the same issue as me, which made me a bit more convinced that I was on right track, and ordered a new lambda sond. Replacement of this sond plus cleaning of the sockets also Connection to the ECU solved that guy's problems. I have so far left the Mass air flow sensor ahead since this was replaced 2015.
However I got some doubt this morning. If I have oil contmination in the lambda socket, which stops the electrical flow into the lambda, it must be contamination all the way up to the solenoids. I cannot see any oil on the wirings, so it seems very strange.
My next step will be to replace the lambda anyway, (alredy ordered) and see whats happening with the codes.
Is it anyone who recognise my problem? Am I on the right track, or am I completely lost, suspecting the lambda system? I would appreciate slightest hint leading to find the root cause. I have to add that the Mercedes has run 280000 km and is otherwise in exellent condition.

Brgds/Gunnar
 

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