My 2001 S430 always has Check Engine Light on, then went away , then come back after one or two days. No Malfunction on computer. No error found when scanned by OBD II scanner. Fuel tank cap confirmed closed properly. Please advise what else could go wrong.

Same problem on my S500/W220/2000. It just came on again. Haven't had it in to the shop yet, but have removed and replaced the fuel cap a few times and the light eventually goes off, but it has started coming back on regularly. Called the service guy and said to bring it in if it stays on for a few days. Please report back here if you learn anything useful. I will do the same. This seems to be something many owners report on a regular basis.

sorry for that year you cantuse the obd II conector.you have to use the mushroom head and the conector is under the hood on the right side drivind directon.where the hood hinge is.It is either under a round plastic cap or under the whole cover

The W220 doesn't have the "mushroom head" connector as on earlier MB's. The OBD connector, on the drivers' underdash panel, is where the scanner should be connected.

If the MIL is lit, and no codes exist, then the fault has to lie in the MIL lamp circuit, or in the PCM itself.

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1989 300 SEL that mostly works, but needs TLC

There are error codes in sytems other than the engine management systems on many cars that can illuminate the CEL. A generic OBDII tester could miss these, even a very good one. Don't know if that is the case on your particular car though.

Use SDS to read the codes.

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

My CEL is coming on every few days now, but staying on for only a few hours at a time (2-18hrs.). Very strange, but the car still drives and sounds like a dream machine. Weird...

I'm going to get an oil change in 1,500 miles and will have the dealer plug it in and see what they can find. If the CEL is not on though, I fear they will not be able to find anything. I'll try to take it in when the light is on, but it goes out quickely. Hope the damn thing doesn't blow-up before I get it in.

If the CEL WAS on, the code (s ) will remain in memory for quite some time.

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2007 C 230 Sport.

Thanks! Now I hope nothing really bad happens before I can get into the shop.

After learned generic OBDII scanner won't work on Mercedes, then bought a scanner for Mercedes($46), it read erroe code P 2017 and P 2068 which reflects a faulty MAF, Thanks "M.B.DOC.". CEL gone after MAF replaced .

i have a good scanner,and have a code p0170,and a dealer said i needed a air flow meeter.my scanner said nothing about it having a problem.? where did yoy get a scanner for mercedes for 49 dollars.

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What is an MAF? Some type of air filter?

MAF = Mass Airflow Meter.
It measures the amount of air going into the engine, gives this information to the computer, & the computer adds the correct amount of fuel with the air.
Bad MAF = poor running engine.

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2007 C 230 Sport.

Bought the scanner for Mercedes S & E class from eBay. Pls see the following Link.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=4588588912&sspagename=STRK%3AMEWN%3AIT