Here's a doozy to try and figure out.......
 

Hello everybody.......I thought I'd ask here first to get some opinions from people that I'm sure forgot more about Mercedes than I'll probably ever know.

I have an 89 300E that I've owned for about 3 months. Bought it with 168k and now I'm up to 180k. Here is a strange little quirk that just came up.........since I bought the car, when the "CHECK ENGINE" light came on, I get out of the car and walk over to the right marker light and give it a smack so the marker light pops on and then there is no more "CHECK ENGINE" light.

NOW, when I do my routine with the marker light, the "Check Engine" light goes off, and about 3 minutes later comes on and just stares at me for the duration of my trip. Marker light is still on and all other bulbs are intact.

Also as of late, when she's warmed up and been driven for a little while, trying to crank her up again usually entails 2 or 3 false starts, and then she'll turn over sometimes dying out on me when I go up the road a bit. After she dies out, she'll restart no problem and then everything is fine from then on.....

If this has happened to anybody, any thoughts and suggestions would be graciously accepted.

The check engine light could possibly be the O2 Sensor gone bad. The problem with the idle and starting sounds like a problem I had with my idle air control valve sticking shut. Take the IAV out and soak it in cleaning fluid for awhile and see if that frees up the movement of the valve.

Pull up the passenger side front carpet and check the O2 sensor connection that is under there. If it is not corroded and connected firmly get a Duty Cycle meter and check Duty Cycle at pin 3 of the diagnostic connector on the EZL module on the drivers side fenderwell. It should be a multiple of 10%.

Post the results here and we will point you toward the offending circuit.

Good luck,

Hopefully some jerk didnt move the placement of the instrument bulbs to conceal a problem with the car before selling it. I would start the car and pull a tail light bulb while the lights are on and see which one lights up on the dash. And check the others too before you chase a ghost. :rolleyes:

gpracer,

Good call. I don't think anyone would change them intentionally because a light bulb out is much less serious than a check engine light. It could have happened by accident though. Makes a lot of sense.

Have a great day,

The only reason I mentioned it is cause I had the dash out and had to pay attention to where the bulbs go, since some popped out upon removal of the inst. cluster. Plus if some loser wanted to sell a car after an accident and the srs light was on, just change the order of the bulbs or take em out. But the bulb light and check enging light sound suspicious. Almost as if the bulb out light is in the check engine spot. Eh, who knows. :o