02 sensor code help

[esscameron]

Hey all, I have a 2015 M4 that’s been fbo for over a year and I’ve never had a problem with CEL’s until recent months.

My codes right now are:

12B102 - Oxygen sensor heating before catalytic converter, activation: Short circuit to ground.
12B202 - Oxygen sensor heating before catalytic converter 2, activation: Short circuit to ground.
12B302 - Oxygen sensor heating after catalytic converter, activation: Short circuit to ground.
12B402 - oxygen sensor heating after catalytic converter 2, activation: Short circuit to ground.
1B5202 - Supply, terminal 15N_1: Short circuit to ground.

I firstly had my shop replace the Integrated Supply Module with a used one on eBay but that didn’t solve anything. Then we replaced just the two upstream sensors with brand new parts, no luck. And I just checked the fuses and don’t see any of the 30 amps blown. I’m a bit stumped at this point and not sure what it could be. Any help would be greatly appreciated.

[Himraj_M3]

Hey bro ever figured out this issue? I’ve replaced the ISM but im still getting these codes.

[b_w.]

Everything plugged fully into the dme? I found that can cause the short circuit fault.

[theweebabySeamus]

Check the fuses for the o2's/module, if there is one?