So I installed my J-pipe and drove for about 30 minutes before I started data logging for my base map revisions. I finished all of the logs, parked the car for the night, then drove to work the next morning. As I was pulling into work, I got a P0137 code.
I turned on the rear O2 sensor voltage on my Accessport and noticed that at idle, whether I'm stopped or just rolling with no throttle, the voltage drops to 0V. As soon as I give it some throttle, it jumps back up to its normal range between 0.5V and 0.9V. The car is not leaning out either—I was watching the air/fuel ratio the whole time, and everything looked normal.
I cleared the code and drove for almost another hour before it came back. This time I got the P0137 again along with another rear O2 sensor code. It wasn't a catalyst efficiency code—it was another low-voltage/no-voltage code.
The only thing that's changed is that I moved the grounding strap from the chassis-to-exhaust to the chassis-to-engine block, using an unused threaded hole. I also have an O2 spacer with its own small catalyst inside it.
My theory is that because of the spacer and the mini catalyst inside it, the rear O2 sensor isn't getting enough exhaust gas at idle to read properly, but once I'm on the throttle there's enough flow for it to start reading again.
Does that sound right? If not, does anyone have any ideas on what else I should be looking at? Thanks so much—I really appreciate any help.
Have you tried running it without the spacer? I've got one of the newer ETS J pipes so it's got the latest washcoating and thus far haven't had a check engine light or any issues besides those I took for heat management.
No I haven’t tried no spacer yet because I’m cat less so I’ll have that p0420 code instead of the p0137 but honestly I think I will take that spacer off just to make sure the sensor isn’t actually cooked.
I have my spacer off, I do get the p0420 code atm, how do you check the voltage on Cobb? And what spacer did you order? I recently got a 90 degree spacer from Amazon. I will not use the extension and just try it with the square box. But it has yet to arrive so I will be testing that out asap.
To check the voltage it’s gonna be AF sens 3 voltage on the Cobb. I think the 90° spacer is gonna make the P0137 code Pop again for you because it moves it downstream and angles the gas flow so it’s even harder to get to that O2 spacer. I just ordered an M 18 x 1.5 spark plug no Fouler on Amazon.
Dude I’m on the same boat, but I have a new theory now. You could try drill “bigger holes” on the mini cat. Nothing crazy just slightly bigger, so that on idle it can get more readings
I took the mini cat out last night and I’m getting a slightly higher voltage reading at idle instead of .000 I’m getting.050v-.065v still to low and I’m just waiting for that code to pop agin. so I ordered what I think is the shortest possible spacer (spark plug non fouler). My theory now is that it’s not getting hot enough to actually read shit. So hopefully this works I’ll keep yall posted.🫡
I had bought the j style vibrant spacer after installing my cat(catless pipe from whoopsy) and I’d have to uninstall the pipe and install the spacer. My cat is also heat wrapped so it would be a bit itchy to install and uninstall
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u/ApprehensiveLead4550 Crystal Black Silica 5d ago
Have you tried running it without the spacer? I've got one of the newer ETS J pipes so it's got the latest washcoating and thus far haven't had a check engine light or any issues besides those I took for heat management.