Hello - daughter bought an 07 HHR LT, 2.2L automatic and there is a burnt piece of wiring harness that is hanging down at the rear of the engine and towards the the passenger's side - it looks to have been burnt on the exhaust and is now hanging down. Any idea of what that wiring goes to and where the other end might be so I can splice it back together?

I believe it to be this part of the harness (found this pic from the forum when searching and circled what I think it is)



Any chance it's the rear O2 sensor as we've got a code P0420 catalyst below efficiency that could possibly be no downstream O2 sensor (haven't logged live data to see if it's working yet) - going to dig into it tomorrow afternoon but thought I might see if anyone knows where those wires go to.

 

I would follow that burnt wire and see where it goes. We can only guess. My initial thought was an O2 sensor.

 

It's hanging down loose - quick look didn't see where the loose end should go...

 

That wire goes down past the water pump, behind the engine to the speed sensor on the transmission

P0420 is usually related to a clogged catalytic converter.

 

P0420 proves there is a #2 O2 sensor, that is working, telling you the cat is dead. If the O2 sensor had a problem it would throw a code.
If it is hanging there, the other end must be hanging too. What doesn't work? A broken cable must go somewhere.
I hope the car was really cheap and she has a lot of money budgeted to fix it.

 

My question is why did the harness get burnt. Has there been work done? They are secured away from heat but sometimes guys fail to secure them after a repair.

 

What you've circled is on the passenger side, as Oldblue noted. No oxygen sensors over there.