02 Sensor Problems. Please help!

[edgy77]

Alright. I replaced the 02 a while ago. And it's never worked right. P1120 is the code I'm getting. Just fixed the wiring that the idiot previous owner messed up for the 02. Battery reset the ecu, got everything back together. No check engine light. Scanned it. No check engine light. Went for a good 20 minute drive. Including a few pulls. Came back. Checked again with the scanner, no cel or codes at all. Shut car off. Hangout for a bit. Then go out again. 20 mins into my 30 minute arrival destination. Check engine comes back on. So I scanned it again. And P1120 came back on. Any help?! It's a brand new 02 sensor. And good wiring. It's weird cause the check engine light stayed away but came back an hour later.

[vavJETTAw36]

What's the full code and description?


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[ruiz]

Maybe. It's. Your. ECU? I would check your harness for any cuts. Are you getting any shorts?

[getslideways]

which primary sensor did you change, the driver or the passenger?

[edgy77]

I changed the drivers side primary 02. That's what the code is calling for. The code description is heater circuit short. I opened all the wiring leading to where the 02 sensor plug plugs into the main harness and there was broken wires. And we fixed them. Didn't look much farther then that because the problem was fixed for about an hour of drive time. My plan is to first swap In a spare ecu I have laying around. If the code goes away, and won't come back on that ecu. It's a bad ecu. I've had this happen on a jeep Cherokee before. Would throw a code for a bad 02 heater circuit and it would be new and oem and it ended up being a faulty ecu. If the code does come back I'm going to swap the driver and passanger primary 02 to the opposite sides. And if the problem follows to the passanger side. Then it's a after plug 02 problem. So new 02 sensor. If not it's a wiring issue. But any other input is welcome. Maybe something I'm not thinking of.

[edgy77]

Everything else in the car worse great. No shorts, no bad ground feedback through the radio. Nothing. Runs fine. Doesn't misfire or anything. Boost went down a little. But that might be a boost leak which I'm looking at this weekend as well.

[vavJETTAw36]

Oxygen sensor circuit shorts very well can mess up the Ecu.


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[edgy77]

Meaning the ECU could be needing replaced now?

[S4tech2]

Check the wiring at the connector I just had the same issue and it was faulty wiring at the connector on the ecm side. I was getting a fault for slow response if that helps.