Check engine light on my 1994 e320 convertible is on after it was reset,I am told by a mechanic that a new wiring harness is needed,costing around $1000.00.I am not sure if this is what is causing it,I was wondring if anyone else has had this problem and changing the harness was the solution.I know the light comes on for a no of reason but want to make sure of the reason b4 spending a $1000.00 what is puzzling me is that it came on after I pumped gas,this is a common problem in BMW if the gas cap is not set right.
All your help will be greatly appretiated.
Jay

 

Hi,

The light can come on for hundreds of reasons....not just the gas cap loose.
However you did notice it after refuelling so maybe the fuel is the cause.

Key to deciding if the harness is at fualt is to understand what the code DTC is that caused the light to come on. Each code identifies a potential problem.

Your car is before the introduction of the OBDII standard and therefore you may need to get the codes read at an MB dealer. We are looking for codes like Pxxxx where x are numbers. e.g. P0105

MB of various typoes did have problems with the engine wiring harness (injector lead insulation) causing misfire so if a misfire show up then the likelyhood of the wiring harness being at fault is increased but a misfire could also be caused by bad fuel etc.

Eliminate bad fuel (by using it if the car appears to be running OK) and refuel. Get the CEL light reset (again) at the same time you get the codes read. Then see if the light comes back. This shoiuld eliminate bad fuel + we will have more info to go on.

Could be many things (expensive) unless you can eliminate some by knowing the DTC.

Stuart.

 

Yes it may have been the gas cap that got lose and eventually it's going to reset itself. other factors that might trigger the CEL is bad 02 sensor or MAF. Definitely get a second oppinion from other shop. Hope this helps