I recently bought a 2001 slk 320 with 45k miles, my check engine light went on and i brought it to the mercedes service to check it out. the diagnostic results were that two of my oxygen sensors were out, my ignition coil needed to be replaced, and two of my spark plugs were completely out. My warranty is willing to only cover half of the cost and ofcourse i have no choice but to pay the other half. I simply want a heads up and any suggestions/solutions for any other problems that commonly happen on this year and or model so that i wont be surprised.

 

Hi,

Diagnostic results do not categorically state that you need two new plugs, two new ignition coils, two new oxygen sensors etc.
In principle diagnostic codes indicate (for instance) a misfire on cylinders 2 and 4. It is then up to the technician to determine what the cause of the misfire is. It may well be a faulty plug or coil but on the other hand it could also be due to a number of otrher causes.
There are specific codes for faulty O2 sensors but these are once again confirmed by technician input after looking at the O2 sensor waveform. Peak voltage and frequerncy of sample etc.

I do not consider these to be "normal" faults at 45K on a SLK320 but of course COULD occur at any time. My similar SLK and S class are now at 100k without having missed a beat. The SLK is still on its original plugs (platinum) since there is absolutely nothing wrong with them although they must now be on borrowed time.

Plugs are normally changed at somewhere between 50 and 75k dependent upon market. There are 12 plugs and they work out VERY expensive because fitting time is considerable.

The most likely REGULAR fault on all MB's causing intermittent misfire is the MAF Mass Airflow Sensor. These regular fail (or sometimes can be revived with cleaning) at less than 50k but the diagnostic signature is very clear.

Could there be some "commercial" interests here?

Hope this helps.
Stuart

 

Thank you for the reply i will definatly inquire about it to the service department, but what do you mean by commercial intrest?

 

Excuse my interest. I think, reading between the lines, he is saying the dealership is selling you more than you may need to repair your vehicle.

 

Spot on!