Logging for a possible leak or bad O2?

[ray7792]

I got a P0296 code (Post Cat, lean reading from rear O2), but I don't think I have an exhaust leak. Code came pretty randomly after not having the code for roughly 3 months since I changed my Overpipe to better fit my headers.

I cleared the code but pedal has a slight deadspot

My LTFT seem to be fine, below 4% throughout.
AFR is still the same from before getting the code and after

Could it still be an exhaust leak even though trims and AFR hasn't changed?

Maybe it is an issue with the rear O2 sensor itself, is there any way I can log using OFT to test for a bad O2? Is it possible that an incorrect spacer impacts this in anyway? I guess I don't need the spacer anymore since I can just disable the post cat, Rich fuel trim code in romraider. Any harm in removing or leaving the spacer there?

Thank you!

[steve99]

Originally Posted by ray7792

I got a P0296 code (Post Cat, lean reading from rear O2), but I don't think I have an exhaust leak. Code came pretty randomly after not having the code for roughly 3 months since I changed my Overpipe to better fit my headers.

I cleared the code but pedal has a slight deadspot

My LTFT seem to be fine, below 4% throughout.
AFR is still the same from before getting the code and after

Could it still be an exhaust leak even though trims and AFR hasn't changed?

Maybe it is an issue with the rear O2 sensor itself, is there any way I can log using OFT to test for a bad O2? Is it possible that an incorrect spacer impacts this in anyway? I guess I don't need the spacer anymore since I can just disable the post cat, Rich fuel trim code in romraider. Any harm in removing or leaving the spacer there?

Thank you!

if you running a tune for catless headers it shouldchave p0240 cat efficiency disabled.

so you shoul not need spacer which may be causing second o2 sensor to read lean causing your p0296 code.

try removing spacer.

with of you can monitor second o2 sensor using the Wideband AFR log parameter. the normal AFR is front sensor and commanded afr is what ecu is asking for ie target afr.
the wideband may be a bit off as its set up for an Bosh sensor but should tell you if its working.

[ray7792]

Hm thanks Steve, can always count on you!

I'll log, remove spacer, and relog to compare I guess.

Thank you!

[ChuckD]

In previous cars I've had a visual inspection yielded the location of exhaust leaks. Example was when I installed headers on my firebird I ended up with a exhaust leak between the head and one of the exhaust ports. There was a slight bit of black soot there and i could actually hear it as a "tif tif tif" noise.

Good luck.
ChuckD