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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53848
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Mercedes C230: you reset the check-engine light..gas cap

Customer Question

How do you reset the check-engine light on a Mercedes C230 1998 when there seems to be absolutely no apparent problems with the car
and the gas cap is in place,
Submitted: 7 years ago.
Category: Mercedes
Expert:  Marty replied 7 years ago.

HiCustomer you are going to first need to have the car connected to a diagnostic tester to see what fault code or codes are turning the check engine light on. Once you know the fault codes you can take steps to correct the problem. The check engine light will not necessarily result in poor engine running in fact it rarely does. You could have a fault in the fuel evaporative system or egr system or secondary air injection system, all of which may not result in poor running. Let me know if you have any questions.



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Customer: replied 7 years ago.
I thought you would say something like un plug battery ,on hold gas pedal 1 minutes or switch key on and off ten times? ot go see a mecanic get a diagnostic gizmo installed in the socket for diagnostics.all I want to know is how to reset the FAULT .If i qwanted topay to go to the garage You should asume i wouldn't have asked a Proffessional mecanic ON-Line
Expert:  Marty replied 7 years ago.

I wish you would have made that clear in your original question but the fact is until you know what the fault codes are and repair the problem the light will simply come back on again after you reset it. There is no way to reset the light without erasing the fault memory with a scan tool. You can go to most AutoZone stores and have your fault codes read at no charge. Once you get the codes post them back to this question and I'll advise you on what might be the problem.



Customer: replied 7 years ago.

I live in Canada and we don't have any Autozone free diagnostic what-evers,

no I don't know which fault it was but MY son would like to reset the check-engine in case it was just a minor temporary problem,we live in temperatures that vary in a 24 hour period from -10C and +12 or 15 C ice and frost can cause all sorts of problems,

and tomorrow they say we'll be around- 17C with a wind sheild factor of -30C

so i'm suspecting just a sensor somewhere on the car that gave a check-engine problem but there might not really be one.I'd like to know how to reset the light once the car has been sitting in a garage for 12 to 16 hours just to see if the problem will come back..Frost does different problem to computors but once you put heat to the defective component the problems go away..

Expert:  Marty replied 7 years ago.
I honestly don't think you'll have any luck on a 98. On the earlier cars you could disconnect the battery and touch the cable ends together for a few minutes to drain the memory in the control unit but I doubt that will be effective on a 98. If the fault was intermittent and is now gone the light will clear itself after numerous fault free drive cycles. There are also inexpensive code readers on the market that can read and erase fault codes. I cannot recommend any particular reader as I don't use them but you should be able to do a Google search and come up with a popular choice. Here's one I found on eBay.