About 1 year ago, my check engine light came on, which the dealer was unable to remedy for more than a week at a time. After replacing both O2 sensors and the catalytic converter, the light has been off for 9 months, until about a week ago. The light came on after sitting parked for a couple of days, and the engine has been slightly rougher ever since (it does have 154k on it). The dealer initially said the code was from a bad O2 sensor. After being reminded that they replaced both O2 sensors and the CAT within the last year, they said they would check it again. A short time later they called back and said it was actually a short in the engine compartment wiring harness. They said the vehicle was unsafe to drive and we should take it to their used center and see what we could get for it, or if we wanted to fix it the part would be $1000, and 12 hours of labor. Anyone heard of this before?

Thanks in advance,
-Sean Donnelly

In other words, they don't know what is wrong and would you buy a car from them, please? OR They screwed up.

You don't say where you live, but I would look for a shop that has real mechanics, like any indie Volvo shop.

Could you tell us what code is setting off the CEL? When was the last time you had a basic tune up?

Klaus
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1995 854T and 1998 V70R

I'll have to try our local mechanic, we only went to the dealer since they had done the work. I'm not sure what the exact codes are, but they point to the O2 sensors and CAT, but apparently the individual components test out fine. Do you think it's reasonable for them to replace the entire wiring harness instead of rooting out the problem more precisely? Would it really take 12 hours to do this?

Thanks again,
-Sean Donnelly

You would be the first person to have the complete wiring harness replaced. No one on this board has ever reported doing so. The only portion of the wiring harness that has a weakness is the red wire from the battery to the main harness.
Usually, when there is an O2/CAT CEL, there is a vacuum leak close to the intake manifold.

Klaus
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1995 854T and 1998 V70R