My 1998 SLK 230 Kompressor is acting weird. First, my gasoline tank gauge is not showing full when filled. It shows half full. Okay, I can live with that. Then the dreaded Check Engine light came on. My mechanic couldn't find a problem, but E10 showed up in the test, but he didn't know what it meant. Then, I was driving along and the radio quit and few minutes later the engine started idling really loud and died. After sitting a few hours I was able to drive it for a little while before the radio died and a few minutes later the car died again. I was able to get it to another mechanic who thought it was an alternator, but when he put it in that was not the problem. He is talking about bypassing something or other. Has anyone had this problem?

Fuel tank sending units are a problem on MOST newer cars! NOT just MB's. That COULD be due to the additives that the gas companies are using to reduce emissions!

AS far as the check engine goes, ANYONE with an ODB2 scanner should be able to find the problem (code).

ONLY! ON the 1998 SLK there is a alternator by-pass relay that can cause the car not to charge. THAT relay was designed to cut off the alternator in case of an accident! THEY didn't work well & MB discontinued that design before the 1999's came out.

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Thank you for your reply. In case you couldn't tell, I know nothing about my car. I will use the excuse that I am a female. If the alternator by-pass relay is the problem what is the solution? Is this something you can disconnect or replace with something else?

Just a long shot, regarding the engine rough running....could it be the OVP (over voltage protection) relay causing the problem?.

I thought I would check in to say it was the relay switch that was the problem. Unfortunately, I now have a brand new alternator installed that I did not need and am out $225 as well as the labor to install it. My husband told the mechanic that the alternator was the problem so he ordered one. I would advise you to let the mechanic determine the problem instead of your husband. We can only get $45 for the old alternator so I guess I will just keep the spare part in case I actually have an alternator problem. Thanks for your help.