Warning lights. The first port of call.

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Feb 8, 2007
Portsmouth, Hampshire.
E55K SL500 E250X2 Smart44 Brabus Track car E450Cabriolet X350 Pick up
I thought it was about time to put a thread up about warning lights that may show up on your car from time to time indicating there is something possibly wrong with one of the vehicles systems. There are so many threads on here with the same questions about what to do.

The very first port of call is to check the basics. Battery voltage, condition and make sure the terminals are tight is a good place to start. next are the fuses. It is probably best to check all of them and use the fuse map in the car to refer to what fuses you are checking. On some Mercedes cars there are a fair few fuse boxes so get familiar with what your car has using the handbook. Checking the fuses will also give you a chance to check if there has been any water ingress in any of the fuses boxes or control units.

If your car has diagnostic capabilities then the next thing you need to do is get it plugged in to a diagnostic machine. A Star is the best of all of them for Mercedes but other machines may suffice for uncomplicated issues. When the car is plugged in this will enable the user of the equipment to read the fault codes in the relevant system that has brought the light on. Some codes are very straight forward to read and understand and some are not. It is up to the operator of the diagnostic equipment to fully understand what the codes mean. There are two types of code too. Current and Stored. A current code means there is a fault currently. A stored code is something that has happened but is not necessarily happening right then. Current codes make it much easier to carry on testing with a Star as the vales you may want to look at will be faulting at that precise moment.

As I have said before, fault codes are only half of the information. Live data is the key. The Star can give you all manner of actual values to aid the user in to finding the fault.

Without reading the fault codes and doing some simple checks finding the cause of the fault can be quite tricky. Never just bolt on parts in the hope of fixing it. That never really works and it will cost you ££ in the long run. Do the simple checks first and let a professional do the fault finding is my best advice. To plug in and read codes can be as cheap as £20. A much better option IMO.

I hope this helps members.
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