Ok, my engine light came on a while go and i decided to check it now since my inspection is coming up. I have a 95 240 se with an obdII and using the obd2 checker got front o2 sensor problem. Got that replaced, o2 problem is still coming up. I following the procedure on how to check the if there is any grounding issues using the fsm procedure, and found out that i have wiring problem. So after all the jebbar jabber, has anyone ever had this problem or know how to deal with it? Unplugging the ECU and the oxygen sensor wire, checking between the ecu and ground continuity exists (not good).

Any help would be appreciated.

O yeah, i already searched for this topic in couple of forums.

 

did you reset the ecu after the o2 sensor was replaced.
a friend of mine has a 2000 contour that had his cel come on. it was a bad o2 sensor, so he replaced it but the light stayed on. i reset the ecu and no more light.

 

Yes, i did. Many times. I also check the the voltage on the o2 sensor, and it was reading between .3 to .6 volts. While running at 2000 rpm under no load.

 

If you are showing continuity on the ground wire I would suggest just applying a new ground somewhere to the chassis.

 

The single wire from the oxygen sensor has a shield around, i believe, which is grounded and the sensor uses its body as ground to close the loop. So, i don't know what you mean by getting a new ground? You mean to take out the shield ground?

 

Never mind I thought you were talking about the second sensor that plugs into the harness after the CAT. I missed the part where you said front sensor...

 

Actually that gives me an idea, not the new ground. But i can remove the grounded shield for wire and have no contact with the chassis ground.

 

Let us know if your idea works...

 

It worked. The ground terminal on the engine that is used to ground the shield for the green wire (oxygen sensor wire) was removed and engine light disappeared. I'm just going to cover the terminal with electric tape and the won't have any problems with it, hopefully, since it is only a ground for the shield.

Thanks for the tip bigvinnie.

 

Hey man it was all you. I just know when grounds go bad to apply a new ground wire...