Check engine light

[Chas]

S class W220 2001 S320 petrol 2001, 95k miles

My check engine light is on and car is in limp mode ( reduced power)

It starts ok and revs are stable ( Full MB service history)

Any any ideas? Its petrol so no EGR valve, could it be a dirty blocked intake manifold?
I have disconnected battery and it clears the check engine warning light temporarily, it reappears the next day !

Thanks

 

[xp2500]

As everyone else says... STAR Diagnostics.

Does the car have a MAF sensor, perhaps that could be faulty ? :S

 

[Chas]

I suspect its the MAF, will let you know, thanks

 

[Chas]

The findings yesterday were" B37 POTENTIOMETER (THROTTLE PEDAL) stored fault, actuation and actual test within spec,
Cleared fault memory and tested, no fault "
Car running fine ...........so far

Update

Started car up this morning same symptoms as before !


I disconnected the battery for an hour, reconnected, started her up and engine check light not showing, but still reduced throttle power. Switched ignition off, took key out, started her up again and running perfect

Must be one of those annoying electrical things ?

 

[BlackC55]

You probably need a new throttle pedal. Common issue.

 

[Chas]

Is the throttle pedal plug and play, I have disconnected the old one, will another one work ok if I just plug it in? Thanks

 

[BlackC55]

Yes, plug and play.

 

[Chas]

Many thanks, problem has returned again, will keep you updated when I get plug the new one in ........

 

[Chas]

Update

Disconnected battery again.......... removed and unplugged the throttle pedal, reconnected pedal, fired her up, took a 20 mile drive in sports mode ( semi auto) went like a dream no errors!
Maybe the sensor plug /socket had residue or something ? Could I have removed oxidation and restored the electrical current?
__________________

 

[Chas]

Touch wood, still running sweet today, no errors or issues

 

[Chas]

Update

My car is still ok, MB tech said they had another W220 with exactly the same problem as mine and asked if I would bring my car in to compare readouts. I duly oblidged, the other car is still showing P0120 code in STAR, mine oddly enough flashes up the same code for a second on STAR then shows no fault code !

Fingers crossed mine is still ok