[335ji]

Got my BMS downpipes installed and the tech said that one of the rear O2 sensor (gray) doesn't fit. They ended up plugging it and said that it is not required (other rear is on). I have been driving around and it seems ok, JB4 clears the code (2c9f). From what I understand the rears only monitor the cats.

Is it ok to run without one rear O2 sensor? Anyone run into this issue?

[Mike@N54Tuning.com]

Originally Posted by 335ji

Got my BMS downpipes installed and the tech said that one of the rear O2 sensor (gray) doesn't fit. They ended up plugging it and said that it is not required (other rear is on). I have been driving around and it seems ok, JB4 clears the code (2c9f). From what I understand the rears only monitor the cats.

Is it ok to run without one rear O2 sensor? Anyone run into this issue?

Thats bizarre.. How does it not fit?

If I remember correctly with the BMS downpipes you have to unclip the o2 sensor wire so you have more length to get it to the bung. Is that what the issue was?

Leaving an o2 sensor dangling under the car not installed correctly does not seem like the correct way to install.

Mike

[Tiago@VRSF]

It is required, make sure it gets plugged in one way or another.

[shadow191]

I think the rear O2's do more than that. This comes up in discussions regarding the DPFix, but the rears are used for fuel trim adaptations? So you'll eventually end up with A/F being off between the two banks if one is unplugged or not working.

And what part didn't fit? Was it a wire issue or was the bung the problem? I've never heard of the rear O2 not fitting.

Originally Posted by 335ji

Got my BMS downpipes installed and the tech said that one of the rear O2 sensor (gray) doesn't fit. They ended up plugging it and said that it is not required (other rear is on). I have been driving around and it seems ok, JB4 clears the code (2c9f). From what I understand the rears only monitor the cats.

Is it ok to run without one rear O2 sensor? Anyone run into this issue?

[Jeff@TopGearSolutions]

Yea they are required for sure to keep AFR in check.

I'd start questioning their install procedure.

What aspect doesn't fit? Are the threads good? Is it hitting the vehicle? Did they clock the downpipes correctly for clearance? The most popular mistake during downpipe installation is not clocking the downpipes appropriately for maximum clearance. A variance of a few degrees counter clockwise or clockwise will make a big difference. All they need to do is loosen up the V Band clamps at the turbo's and clock appropriately.

[335ji]

Originally Posted by shadow191

And what part didn't fit? Was it a wire issue or was the bung the problem? I've never heard of the rear O2 not fitting.

The issue was that the sensor was too close to the transmission and they did not want to damage it so they removed it.

[Mike@N54Tuning.com]

Originally Posted by 335ji

The issue was that the sensor was too close to the transmission and they did not want to damage it so they removed it.

I would go back and have them clock the pipe slightly to move the sensor away (if possible) I am not sure how close it is, but a pic would help. Close should be okay but touching obviously not.

Like other have mentioned you shouldn't leave the sensor off. May be okay as a short term solution but I would not run a car that way as Jeff correctly pointed out the AFR may become wonky.

Mike

[N54Bob1988]

When i inatalled my bms pipes, i put the rear sensors on the pipe prior to installing to make fitting easier, never had an issue.. dug up an old photo for all to see,

[335NJ]

They were used BMS pipes I assume? Since they haven't sold their DPs for a good amount of time now.

If they're not used, they're likely knockoffs which would explain the poor fitment.