Hello everyone… I could use a little help diagnosing a cell issue. I have a 08’ with PPE Headers, RR Intake, JoeZ exhaust (with Magnaflow cats welded in before the O2’s), and a RR tune. All mods have been on the car for over 2 years with no issues.

Over the past 10 months, at random times, I keep receiving the same cell codes

P0136 – (Bank 1 Sensor 2) – O2 sensor circuit malfunction
P0137 – (Bank 1 Sensor 2) – O2 sensor circuit low volts
P0139 – (Bank 1 Sensor 2) – O2 sensor CKT slow response
P0156 – (Bank 2 Sensor 2) – O2 sensor circuit malfunction
P0157 – (Bank 2 Sensor 2) - O2 sensor circuit low volts
P0159 – (Bank 2 Sensor 2) - O2 sensor CKT slow response

Obviously the codes point to sensor 2 on both sides, but what are the odds that both O2 sensors go out at the same time? Could it be the O2 conditioner for the PPE headers? Could it be the RR Tune? Or maybe, both O2 sensors did go out at the same time?

What do you guys think? Any help is appreciated!

 

The ECM occasionally sends extra fuel down the exhaust to measure catalyst efficiency. If the sensor detects no change, it sets a DTC. This is done intentionally to make it harder to fool the ECM into believing cats are present and working when they are not. There's a pretty extensive write up on this in the Factory Service Manual.

 

Hey lobuxracer! thank you for the reply... I appreciate it! What you said makes sense, but why would everything be working correctly with no cell lights for over a year and then all of a sudden, I get ~3 codes per month that all point to both of the secondary O2 sensors?

 

The RR tune should've eliminated the CEL for cats and there shouldn't have been any need for a O2 conditioner with the tune. I think I remember a while back someone was having issues because he had the O2 conditioner hooked up at the same time with the tune and it was causing issues with the CEL coming on?

 

thats what I thought?

is there a reason for OP to run both?

 

Thanks for the reply! I actually had the PPE headers with the conditioners installed before I purchased the tune. When I bought the tune, I had a phone conversation with Ravi from RR and I asked him if it would be a problem running the conditioner with the tune being that the tune should eliminate any chance of a cell anyway. Ravi said it was redundant, but shouldn't make any difference at all. I've been running the tune for about 2 years now. For over a year the car never saw a single CEL, but over the last 7 months or so, I've been getting about 3 codes per month at random times. The part that stumps me is that every single code points to BOTH of the secondary O2's.

 

Resurrecting this, what was the fix?

 

Despite the fact that Ravi says you don’t need to, I had to replace the conditioner. Once I did that, everything was perfect.

 

Appreciate it. I'm having a similar issue except I don't have headers or conditioners.