I found that the ML320 engine (112 engine) has a system which in certain occassions it will turn on. This system is called "Cylinder Shutoff". This happens on many occassions (eg. going to fast, bad O2 sensors). When the engine goes to this mode, also called "Limp-Home" mode, cylinders 2, 3 and 5 are completely shut off. All kinds of misfires and tremendous loss of power.

I had this problem and took the car to the dealer. Mind you, I have 104k miles on the car so warranty is gone......The dealer's opinion on diagnosing the CEL was that they first needed to change the spark plugs ($500.00 cost) and also they needed to change the left cat. converter ($1750.00). They knew the engine was misfiring on 2, 3 and 5 and I knew the same because I had a friend pull the codes.

Now, I think the dealer was trying to pull a quick one.

Right now I ordered 12 new spark plugs and four O2 sensors...total $442.50.

Let me know if you need info on the "cylinder shutoff" condition. I pulled literature from the MB start tek web..

Regards,

Ric

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Ric
Ann Arbor
2000 ML320, 172k

If you think education is expensive, try ignorance.