[jcarv20]

Hello all,

I've gone thru some threads and googled the check engine code i'm getting "12B302 - Oxygen sensor heating after catalytic converter, activation: Short circuit to earth" and I'm trying to determine the best order to troubleshoot this, any help would be appreciated. I understand there are a few possibilities such as the Integrated Supply Module located on the passenger side located near the battery terminals (part number is 12637591534), but also it could be one of the O2 sensors (more likely pre-cat; I have a catless dp with MHD Stage 2+), I also heard maybe a fuse? (Not sure which). I've had the downpipe on for probably close to a year but this check engine code has only come up the last couple weeks. Car doesn't really drive any different but I'd like to resolve any issues as we all know it could lead to something else further down the road. Any input is highly appreciated.

[thejeremyman9]

Why do you think its the precat O2 sensor when the code is for the O2 after the cat? I would say try the simple things first like checking the connections and the wiring. It could just be the O2 itself as well.

[jcarv20]

Originally Posted by thejeremyman9

Why do you think its the precat O2 sensor when the code is for the O2 after the cat? I would say try the simple things first like checking the connections and the wiring. It could just be the O2 itself as well.

Just going off what I've read; doesn't make much sense to me either why it would be the pre-cat not the post cat O2.

[n55david]

its the post cat 02

you have a line break.. I have the same code

[jcarv20]

Originally Posted by Phantom10R

its the post cat 02

you have a line break.. I have the same code

Hey - did just swapping out the post cat sensor resolve your issue? I was trying to check the fuses and location of the ISM but I'm not sure where either is, I can't find an accurate diagram of an F32.

[n55david]

Originally Posted by jcarv20

Hey - did just swapping out the post cat sensor resolve your issue? I was trying to check the fuses and location of the ISM but I'm not sure where either is, I can't find an accurate diagram of an F32.

I haven't swapped it yet lol.. being lazy

[jcarv20]

Originally Posted by Phantom10R

I haven't swapped it yet lol.. being lazy

LoL fair enough, I feel ya.

[5w20]

Originally Posted by jcarv20

Hey - did just swapping out the post cat sensor resolve your issue? I was trying to check the fuses and location of the ISM but I'm not sure where either is, I can't find an accurate diagram of an F32.

I had this same code. You can verify if it's the sensor with a multimeter, but if you like to wing it then replace the REAR O2 sensor. I had the same code, but I verified that the sensor was my problem. Replace sensor and code is gone.