LNF rear O2 sensor dumping fuel to save cat with COT set to all to 1

[GoodSpeed150]

Hey guys, I installed a catless downpipe that doesn't include a rear O2 bung. So the rear O2 is zip tied to the chassis. The COT is set to all 1's in HP tuners. Problem is you can see on the RPD that the AFR fluctuates from where it should be down to 10.8 anytime the car is running (cruise, idle, and WOT). This causes the car to slightly hesitate and even buck when going that rich. Im assuming its doing this because its thinking the cat is overheating. When I unplug the rear sensor everything is fine, problem is resolved. I'd like to keep the rear O2 plugged in for emissions reasons but don't want to have this problem. What do you think I can do to resolve this?

[JimmyS]

If you don't have the sensor installed, I think you need to get someone to weld a bung in so you can install the wideband sensor. Without the wideband installed, I'm not sure how you're able to control your A/F ratio. In my opinion you're asking for trouble running without it.

[MikeM173]

The rear o2 he is referencing is probably the second one and NOT the first one which is the air/fuel one.

I would either have a bung welded in, get a different down pipe that had a bung, go back to stock, or just unplug it and disable the check engine codes.

Those are about your only choices.

[GoodSpeed150]

The rear o2 he is referencing is probably the second one and NOT the first one which is the air/fuel one.

I would either have a bung welded in, get a different down pipe that had a bung, go back to stock, or just unplug it and disable the check engine codes.

Those are about your only choices.

I appreciate the help. I thought maybe there was something I could do in HP tuners. Damn LNF's!

[cobaltssoverbooster]

Yes Mike said you can disable the sensor through hpt. It's in the dtc section

[GoodSpeed150]

I know. Problem is I need the o2 heater to pass in order to pass inspection. Im allowed 2 sensors not ready. I know 02 sensor and catalyst won't pass due to the catless DP

[Dr. Nopps]

That's what they are really, really, trying to tell you is possible. Set not just the sensor but also any diagnostics that won't pass or ready up to setting: 3 No Error Reported under your DTC's tab. You should then have zero things not ready or mature and happilly be on your way.

[GoodSpeed150]

That's what they are really, really, trying to tell you is possible. Set not just the sensor but also any diagnostics that won't pass or ready up to setting: 3 No Error Reported under your DTC's tab. You should then have zero things not ready or mature and happilly be on your way.

These Bosch ECU's don't have that option 3 'No Error Reported'...

[cobaltssoverbooster]

These Bosch ECU's don't have that option 3 'No Error Reported'...

yes they do its just re-worded. look for "Disabled"