SweetWaterSurprise

So I had my cat go bad and take out my O2 sensor. I went ahead and ordered a New 63.5MM Berk HFc and new Denso O2 sensor. Installed everything this past Sat and cleared my codes. I tried the ECU reset by pulling the 7.5 Backups fuse and that didn't clear the code at all. Still had the CEL so I used my code reader for the job. Had no CEL for around 60 miles before the CEL came back with the same P0139 codes. I do not have any defoulers on the cat considering how far back the sensor sits in the new HFC. I don't get what the issue could be. Do I need to add a defouler to set the sensor even further back? BTW I have a 07 AP2

SweetWaterSurprise

Anyone have a clue of what I should do here?

TvoS2K

Try to reset it by disconnecting the battery for about 10 minutes

SweetWaterSurprise

I was able to clear the codes with my scan tool, but I still wonder why the ECU fuse reset didn't exactly work like it did before to get rid of CEL

Billman250

Resetting or clearing will do nothing.

Get a right angle 02 spacer and point it towards the front of the car.

It will keep the cel off for a code P420, guaranteed.

As far as your P0139, it wont help.

SweetWaterSurprise

That's my issue. I don't get why a Brand new sensor would still have that specific code (0139) It only took 25 miles this time before the CEL popped up again. From what I have read it's pertaining to a problem with the Bank 1 Sensor 2.

SweetWaterSurprise

At this point I'm not sure what else I can do. Can't seem to shake the P0139 code, new O2 sensor at all. There is no leak that I can find anywhere.

THE REAL DEAL.

new sensors can be faulty or some thing else might be triggering the CEL try cleaning your old one and put it back in see if it makes a differences If the cel is coming on in a same way you might have a bad connector or a wire. but if the CEL is coming on straight away after resetting it your new sensor is no good. I have had this issue a few times but mostly with non genuine ones in the garage. All so the 02 sensor takes an earth from the ecu when cold and when hot from the manifold.

SweetWaterSurprise

Well here is the problem, the old sensor is toast. It was destroyed by the OEM cat eating it up. The CEL doesn't come on for maybe 25 miles after I clear the codes.

SweetWaterSurprise

Can anyone else confirm that DENSO 234-4353 is the correct O2 sensor for the downstream?