Many codes found, now where to start ?

Contour Enthusiasts Group Archives

Well I have had the MIL on for a while now and decided to get the codes scanned. Here's what was found:

-HO2S signal circuit malfunction: P0156.

-HO2S heater circuit malfunction: P0135, P0141, P0155 and P0161.

I find it very hard to believe all these HO2S's have gone for a crap all at once. Is it possible a fuse is blown somewhere to cause this or am I looking at multiple O2 sensor replacement ? Car seems to be running fine without any significant mileage change ...

Originally posted by weasel:
..I find it very hard to believe all these HO2S's have gone for a crap all at once. ..

Me too. Check/change Fuse 13 (20AMP) for O2 sensors in the Power Distribution Box next to the battery.

Originally posted by weasel:
.. Is it possible a fuse is blown somewhere to cause this ..

Yes.

Originally posted by weasel:
Well I have had the MIL on for a while now and decided to get the codes scanned. Here's what was found:

-HO2S signal circuit malfunction: P0156.

-HO2S heater circuit malfunction: P0135, P0141, P0155 and P0161.

I find it very hard to believe all these HO2S's have gone for a crap all at once. Is it possible a fuse is blown somewhere to cause this or am I looking at multiple O2 sensor replacement ? Car seems to be running fine without any significant mileage change ...

Or you could also have one of the heater circuits grounding out the rest. I've seen that happen many times before when I worked at the dealership.

Have fun....

Have fun, gee thanks !!! Well I did some looking and fuse 13 wan in fact blown. I replaced it and it blew again. I traced the first two upstream O2 sensors and didn't notice any wiring problems ( well I traced them into a loom ! ). Haven't checked the last two, but I doubt its a sensor itself. Any ideas where to look to find this ? Known problem areas ??

Inspect the sensor harness to see if one is lying on the exhaust manifold and has melted.

Steve

Will do ... tomorrow though. Raining like a SOB here.

Disconnect the all 4 O2's, put a fuse in, if it still blows you have a problem in the harness. If it doesn't, plug 1 O2 in at a time until the fuse blows, when it blows that is the O2 you need to replace.