TornadoThrower
Member
- Joined
- Apr 3, 2024
- Messages
- 37
- Reaction score
- 2
- Points
- 8
- Buick Ownership
- 1999 Buick Regal GSE
My front upstream O2 sensor that came with the car died, I think it was even factory. Came with the codes PO131 and PO171, and also worse MPG. With my somewhat fancy scan tool, I was able to see that both fuel trim levels were stuck on 1 number and never changed. I bought a Denso O2 sensor and it installed. Fuel trim levels looked fine but I got the PO131 and PO171 code again. Bought another Denso O2 sensor and got it installed because I throw away the other box because they said Denso's a good brand and didn't need to worry. This time, Short Trims were changing but the Long trim was initially stuck on 20 something but eventually revert to 0. I get the PO131 but not the PO171. The car runs great and it never has any stalls and wild revs but my MPG is still worse then normal. After 3+ days of driving and before a battery unplug, I get a whopping 12 MPG. I do have the famous regal problem which is the fuel level sensor (Ex: 2 gallons is 3/4 full), so maybe the MPG is calculated into that equation but I'm certain its not. The PCM used to give me a error code for the Rear O2 sensor but it seems just to forget it and not even care, no matter how many times the PCM resets, honestly that's how I feel about the rear O2 sensor too.
If your curious about the Denso I was (I guess still) using is the "DENSO 2344018".
If your curious about the Denso I was (I guess still) using is the "DENSO 2344018".