hi just bought my first merc a 2003 c220 cdi auto estate. The car drives beautifully but is in limp mode. had codes read and shown no faults. instantly i was thinking MAF, bought MAF fitted - instantly started revving normally great i thought. Took her out for a test drive and within a mile back to limp mode. Had codes read still showing no faults.any ideas on where to look next.

before i fitted the new maf it didnt matter if car was switched on or of the problem was still there.

Thanks for any replies in advance.

 

just to add i did have one code thrown up which was :
voltage supply of circuit 87 has undervoltage.

this was found on the transmission. could that be the problem.

 

You wasted you money bro, a MAF does not produce a electromechanical limp mode.

However you latest scan is zeroing in on the problem--have the transmission scanned with factory or equal software and voila!!

 

Car is going in for star diagnostic on wednesday. I had a guy check car with a top of the range Launch diagnostic for free and it pulled up loads of stored codes which he erased. Only one that was left was

P0105 Pressure sensor plausability (current and stored)

One car was started after codes were removed took for a test drive - it drove perfect for about 2 miles then went. Guy scanned it on return and it showed the above code and :-

P1470 - 32 Charge Pressure Stored Control Variation ( charge pressure too high )

I replaced MAP sensor took for test drive and lasted about 20 miles car was flying. Pulled up outside the house reversed into space tried to rev it in neutral and it had gone again into limp mode.

So my question is after reading up on the high boost pressure it states it can be caused by split hoses etc. Surely this would cause low boost pressure. I would have thought it would be more along the lines of blocked dpf or CAT.
Thanks in advance lee (swansea)

 

Just to add at no point has the engine management light come on.
lee

 

Have you tried disconnecting and reconnecting negative battery terminal? Half the time this solves all my problems

 

hi, i have heard that this can cause more problems than it solves, its just very annoying as it seems to do it when the car is at traffic lights or when i park etc always seems to be when car is either going slow or is stationary when on motorway etc the car is faultless. reckon i could take it to scotland and back as long as i didnt have to stop and the limp mode would not kick in.

With regards to the over boosting error what should i be looking for. have checked the actuator is moving up and down on start up and it does only time it hasnt moved was once out of about ten and at that time it was in limp mode.

many thanks for the reply.lee

 

hi , my car is just the same , what was your problem ?

 

I had slipping going from 4th to5th ,and circuit 87 undervoltage.its been to Mercedes dealer and scanned ,they advised a new conductor plate fitted new conductor plate in g,box,cost £670 they couldn,t say it would fix the problem,but they had it out so went with the new plate.the mechanic told the circuit 87 wasn,t a problem. Having set off with my caravan it seemed ok.with the gears,but reving it going up an hill it got stuck in gear and wouldn,t change up,so stopped for 15 minutes and started and it was back to normal.so got home and read the codes on the trans and it came up with only circuit 87 under voltage again.

 

Find your TCM (passenger footwell in LHD car) and unplug it from the harness. Check the plug and wiring for ATF that has wicked up the wiring harness from the leaky plug on the transmission. When I bought my car it was in limp home mode, no communication with the TCM and circuit 87 undervolt. The TCM was full of atf. Cleaned the TCM and wiring with isopropyl alcohol, cleared the codes in the transmission and it was good as new.

 

Broadis help me if you can

 

Broadis;
I hawe same problem pls help me do you fixed the problem

 

got the error code circuit 87 under voltage,was advised to check the trans control module for oil,non in the loom and none in the tcm.put it all back together,and went for a test drive stuck in limp mode again ,with P2108
internal electric check of component Y3/6Y2 (shift pressure control solenoid valve)has failed.So took out the tcm and checked wiring and plug fitted correctly,cleared code and went for test drive and everything working ok. So don,t know how it fixed itself but might be worth a try, thanks for the replies I got.

Steve