2000 Mercedes E320 Check Engine Light Problem

We have a a 2000 Mercedes E320 Fourmatic with 130,000 miles on it purchased used with 45,000 miles. Our problem began recently with the car not starting sporadically. Went to the dealer and he replaced the starter and the wipers which would not work now ($2000). The next week while driving the check engine light comes on and the car loses power. Car towed and dealers computer says it needs a catalytic converter. Replaced at $600 for part only because of previous problem. Three days later while driving check engine light and loss of power again. Car towed for second time. Dealer says now two plugs bad and replaces them (car had original plugs). Mechanic takes out for drive and check engine light and car loses power again.

Does anyone have any ideas as to what the problem is. You’ve helped me twice before with other problems and have been right on the money.

I would appreciate any responses.


First off, if you are still running on the original plugs, you need a FULL tuneup.
Get new plugs in every cylinder, not just one or two of them.

Next, chances are the problem is either being caused by the Crankshaft Position sensor, or the Relay Control Module. Go with the Crankshaft Position Sensor first.