12B304 - driving me crazy

[heitzke]

A few weeks ago I popped a couple DTC for the secondary 02 sensor:

12AA02
12B021 Lambda probe after catalytic converter 2: signal fixed to lean
12B304 Lambda sensor heating according to catalyst; Control: line break
12B404 Lambda sensor heating after catalyst 2; Control: line break

No big deal, seems like the sensor died so I replaced it with a new one. Cleared the DTC, reset adaptations, ecm, everything. Drove around for 50-75mi and all seemed fine.

Now i'm getting 12B304 popping up after just a few miles of driving. I honestly have no idea what this one means. None of the other DTC codes are popping up but I can't get rid of this one now.

Do/Did I need to do something through ISTA when replacing this? It's rainy all week so otherwise i'd just go get under the car again and make sure it's all situated correctly, but I was really careful with the wire routing, everything plugged in nice and firmly.

Am I missing something here? This seems like a pretty simple thing gone awry.

[heitzke]

Solved. I don't know why it took me so long but the 12B304 is the OTHER secondary 02 sensor. I just didn't understand why both would have died.

The answer as to why they went awry around the same timeframe? Not a clue honestly, but I replaced the bank 1 secondary 02 over the weekend and my code hasn't come back. :shrug: