Limp Home Mode

[Mloclam]

My C220 seems to be stuck (most of the time) in Limp Home Mode. Symptoms: it won't kick down and won't rev beyond approx. 3000 rpm.

Sometimes it starts this way. Sometimes it finishes this way. Sometimes it changes from whatever mode it started in to the other mode.

It has been suggested a probably cause is a faulty MAF sensor or some split pipe. A google search found an article that stated a faulty MAF sensor could be diagnosed if a running engine continues to run after the MAF sensor is disconnected. This advice was generic, not explicitly aimed at MB engines. Is this sound advice? I just started my car, it wouldn't rev beyond 3000 rpm. I then disconnected the electrical connector to the MAF sensor and the car continued to run and continued to not rev beyond 3000 rpm.

 

[OneForTheRoad]

most cars with a knackered maf will revert to pre set settings within the ecu . kinda like a default settings map . taking the plug off can and probably will result in throwing a fault code, whether mb cars need the code cleared before maf regains itself i dont know ?? have a scan done and find out better . maybe someone local on here has a scanner that can help you ...

 

[paul73mt]

I was told if you disconnect the MAF and it runs the same as with it connected then its a good chance it's the MAF but to be 100% you need it plugged it to have the codes read off it

 

[Chrishazle]

My S203 C270 did exactly as you've described a month after I bought it - no kickdown, and could not get above 3K RPM. MAF replaced under warranty, problem solved.

 

[bob6600]

Definitely sounds like a MAF. It is prbably better to get the codes read to ensure you are not wasting money on parts. If you do choose to buy one, get a genuine one (doesn't have to be from MB) or you will end up buying twice.

Also, rather than generic advice, read through this

Lack of power on a CDI. What to do.

 

[Mloclam]

I removed and cleaned the MAF element with a spray of Contact Cleaner. It made no difference to the car's behaviour unfortunately. On the return leg of my weekly round trip Bedford to Glasgow I periodically checked to see if I could accelerate beyond 3K rpm. (I wouldn't normally see a problem as even with restricted power I can cruise at or beyond 80 mph). The car slipped in and out of restricted power maybe 3 or 4 times in the 7 hours I was driving. What is new is that my Cruise Control also stopped and started working a couple of times - I never had a problem with Cruise Control working at all. There was no obvious correlation between the failure of Cruise Control and Restricted Power.

Finally, I get an "ESP Failure" identified now every time I start (I knew I would, ha ha). Trawling through old service history I have a note to the effect that "Steering sensor adjusted to overcome ESP error"). Might the ESP, Cruise Control and Restricted Power issues be related in some way other than "it's an old, knackered car guv"? Can anybody please recommend a STAR diagnostics centre in or around Bedford or Glasgow?

Thanks in advance

 

[alecmascot]

Some of those symptoms sound like the old brake switch issue ?