So I'm getting a P0138 (I think that was it) for high voltage to the rear O2 sensor. It went away for a while, but now It came back. I replaced the O2 sensor figuring that was bad, and didn't fix it. Would the cause be a faulty Converter or possible cut wiring in the harness????

-Mattie

 

Sounds like a bad wiring. But could be a failed cat. Would want to see on a scan tool to track voltage. This would tell you if it is just pegged high or following the primary O2 due to faulty cat. Is it running good, had any strage odors, any signs of heat damage to the cat???

 

it will ocassionally stumble on acceleration, actually it's quite slower than my 2-door I had. and all that was done to that one was a ebay muffler and ATX throttlebody. also with this one, if you rev it and back off...it'll sometimes have a popping sould from the exhaust and bog really low, almost to the point if it dying. Then it will recover, but it's still boggy. I guess that's why I was thinking Bad cat vs. bad wiring. what do you think?

 

From those symptoms I'd disconnect the cat and then try again see if it runs better you'd know for sure then

 

sounds like a clogged, or partially clogged cat, just hollow it.

 

that's what I thought too. I took the cat and pipe off, and the car was rattling pretty bad. so I took the cat and pipe off my parts car which didn't show a bad rear O2 sensor, put it on, turned it on, code still there. What exactly causes the rear O2 sensor to read too many volts? poor wiring, poor gas? why the 'too high volts'?