Check Engine light went off then on again.....
 

Hi I was wondering if anyone can give any insight on my problem.

I have a 95 E420 and the check engine light came on after I started the car. It does not have any power loss and the engine seems to behave normally. I set up an appointment to get it diagnosed but the light went off before I could even go. Then 2 days later it went on again.

a. Is it normal/common for the CEL to turn on and off intermitently?
b. Is the car able to self correct the error?
c. I have read that Auto Zone does the diagnostic for free - how reliable are they compared to the dealer ($100+ per visit) diagnostics?

95 E420
135,000K

I would appreciate any comments or suggestions.

If you can get . . .
 

the codes read for 'free', that's hard to beat. Find out what they are and let's us know.

Yes, the CEL can go on and off: it goes off if the fault has not occured for a certain number of 'trips'. Trips are not just running the car but close.

Without finding the codes, it tough to t/s. Actually WITH some codes, it's still tough but that's the best place to start.

Could be alot of things from an O2 sensor, MAF sensor, fuel trim and/or the dreaded disintigrating 'wiring' harness.

I don't think AutoZone does a 95 E420, only OBDII, 1996 and later. You can either build the code reader (see archives) or perhaps pull it yourself with the built in LED (also see archives). Your car should be a 38 pin connector which does not have the built in LED but some 124/119s have an ancillary 8 pole connector which does have the LED for CE codes. But it's not that hard to build the code reader, and it's a very handy thing to have. But you've got to make sure you build it for the 38 pin and not the 16 pin - different diameter pins.

On and Off
 

Thanks guys,

I will keep you updated.....