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02 sensor help

m-ymk5

New member
Location
Toronto
I recently got a code for the downstream o2 sensor, went to go change it and noticed the wires were damaged... anyways i went ahead and changed the o2 sensor and repaired the wires (cut, strip, crimp, heat shrink), cleared the codes and drove off. after 20 minutes of driving the light came back on and i have the same code plus another two saying shortage and the other said high voltage (cant remember exactly)... why could this be? can i not repair the wires? do i need a new full harness? input would be great as i need to emissions test my car asap!! thanks!!
 

DerekH

Ready to race!
Location
Ontario
I believe that the way the computer uses the o2 sensor is by measuring resistance. So if the wires have changed length or the crimp as added resistance it could screw things up. I see two ways of fixing this. replacing the harness or getting a tune, i was always throwing an o2 sensor code (high flow cat) but once i got tuned it was fine.
 

m-ymk5

New member
Location
Toronto
good to know! lol..

can someone help me find the harness part number/ price? cant find it anywhere

also, when i was changing the sensor the new one was longer than the original one, could this cause the problem? i got it OEM from the dealer. so i dont think it would be the problem but its a thought.
 

DerekH

Ready to race!
Location
Ontario
I could be completely wrong. I'd check with a mechanic or someone who knows for sure before investing in a harness. it may be something as simple as the connecter is corroded.
 

eurocars

5/17/15 - Never forget
Location
Indianapolis
Car(s)
2006 GTI
good to know! lol..

can someone help me find the harness part number/ price? cant find it anywhere

also, when i was changing the sensor the new one was longer than the original one, could this cause the problem? i got it OEM from the dealer. so i dont think it would be the problem but its a thought.

was the part number the same?
 

m-ymk5

New member
Location
Toronto
So it's not the wrong O2 sensor I have the correct one in. And I talked to a few mechanics at work they don't believe the heat shrink crimps should cause resistance at all. I'm thinking Mabye more up the wire harness there's more corrosion? Thoughts?
 

DerekH

Ready to race!
Location
Ontario
How far back did you strip the wires near the damage, they could be corroded under the sheath. Check all the connectors as well, make sure they have no bent pins or corrosion on them. Other than that i really don't know. it could be so many things, i would try to trace the harness as far as you can to make sure its all intact. if it is the same set of codes it could just be the same issue somewhere else.
 

m-ymk5

New member
Location
Toronto
i guess ill have to cut the harness open all the way up and see if there is any more damage but i unwrapped it pretty good to begin with
 

m-ymk5

New member
Location
Toronto
i just spoke with a service guy at vw... he said it could be the harness itself or it may have damaged the acutal ECU... is this a possibility? what do you guys think? ive had this car a week and already cant stand the problems..
 
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