Rear O2 sensor reading
Thread Starter
Race Director
Joined: Dec 2005
Posts: 11,664
Likes: 15
From: Wellsboro Pa
Rear O2 sensor reading
Had the car on diagnostics the other day. Put up all the O2 sensors and 3 of them would change readings periodically. One of the rear sensors read a constant 92.2 with no change. Does that sound right? I recently got a check endine light and was trying to narrow down the reason.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
When in closed loop (non PE) the front 02 voltages should oscillate constantly between .000 and .950--that is normal--The rear 02's are there to check the performance and the condition of the cats--If the cats become overheated the rear 02's will enable the "cat protection system" and briefly richen up the fuel to cool them down--Not quite sure what the rear 02 voltages should read normally--What are the actual codes you are getting if any ?? If you are getting strange readings on the rear 02's it's not as critical as the fronts---If the fronts aren't oscillating then you can get the engine stuck in open loop and it will get poor mileage and run crappy during PT--If the rears are having a problem it's not s bad as the prtection system may not operate--However many tuners disable this system anyway to avoid the extra enrichment when costs you power---BUT if the system is stuck on ENABLE that is a different dtory--you will be getting the enrichment all the time--which will make it run lke a turd---kinda confusing--especiall without knowing which 02 is acting up--Check the voltages at WOT with your scanner or logger and see what it's doing there----
Thread Starter
Race Director
Joined: Dec 2005
Posts: 11,664
Likes: 15
From: Wellsboro Pa
When in closed loop (non PE) the front 02 voltages should oscillate constantly between .000 and .950--that is normal--The rear 02's are there to check the performance and the condition of the cats--If the cats become overheated the rear 02's will enable the "cat protection system" and briefly richen up the fuel to cool them down--Not quite sure what the rear 02 voltages should read normally--What are the actual codes you are getting if any ?? If you are getting strange readings on the rear 02's it's not as critical as the fronts---If the fronts aren't oscillating then you can get the engine stuck in open loop and it will get poor mileage and run crappy during PT--If the rears are having a problem it's not s bad as the prtection system may not operate--However many tuners disable this system anyway to avoid the extra enrichment when costs you power---BUT if the system is stuck on ENABLE that is a different dtory--you will be getting the enrichment all the time--which will make it run lke a turd---kinda confusing--especiall without knowing which 02 is acting up--Check the voltages at WOT with your scanner or logger and see what it's doing there----
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
The most comon issues in setting a p1154/p1134 is from a wiring problem to the sensor or a fouled sensor from silicone or fuel additives such as injector cleaner or octane booster--Could also be water in the fuel--More than likely it is a one-time thing and i woudn't worry about it-If after deleting the code and it re-appears, then i would look into it a bit further--Try another gas station too--quite often they don't change their filters and water separators often enough---
PS : your code is for the front passerger side sensor---
PS : your code is for the front passerger side sensor---
