Reoccurring Oxygen Sensor Issue

[paulo_f80m3]

Hey everyone,

So I have a small issue that I'm dealing with. My post cat o2 sensor has gone for a second time after about 300 miles. The first one lasted about 6k miles.

Error code 12B304. Lambda probe heating after catalytic converter, control: open circuit.

I have stock downpipes with an M Performance exhaust on a VF CS tune with the cold start delete.

Could the cold start delete affect this? Maybe..?
Tune issue? Maybe..?
Bad batch of o2 sensors? Unlikely..?

Any help would be appreciated. Thanks all.

**Update. 2.5k miles later and no CEL on the CS Map from VF. The OEM Bosch sensor is working better than the OE BMW Bosch sensor. Weird. **

[TopJimmy]

Do you add octane booster to your fuel, like Boostane? I leaves a ton of orange dust through your exhaust. I doubt that would clog a sensor after 300mi but it's a maybe. I stopped playing with additives soon as I saw that crud building up.

[paulo_f80m3]

Originally Posted by TopJimmy

Do you add octane booster to your fuel, like Boostane? I leaves a ton of orange dust through your exhaust. I doubt that would clog a sensor after 300mi but it's a maybe. I stopped playing with additives soon as I saw that crud building up.

I do not. Just fuel up with Shell.

[Djdnav]

Was the first replacement a bmw part, or oe? Sometimes the oe ones aren’t stellar quality, despite looking identical.

[paulo_f80m3]

Originally Posted by Djdnav

Was the first replacement a bmw part, or oe? Sometimes the oe ones aren’t stellar quality, despite looking identical.

They were both OEM Replacements.

Any Bosch replacement would work too since its the OE Supplier.

[ntg44]

Different car, but this happened on my 350z. Ended up being a shit tune corroding the sensors.

Maybe contact the tuner and see if you can record/send some logs. My money is on the tune.

[paulo_f80m3]

Originally Posted by ntg44

Different car, but this happened on my 350z. Ended up being a shit tune corroding the sensors.

Maybe contact the tuner and see if you can record/send some logs. My money is on the tune.

Yeah I am leaning toward this. I went back to the factory map. Going to install the new sensor later this week and see the results. If that's the issue I'm done with VF. It's been nothing but issues from the start. I'll be looking elsewhere and taking my 1k mistake to the chest.

[ntg44]

Originally Posted by paulo_f80m3

Yeah I am leaning toward this. I went back to the factory map. Going to install the new sensor later this week and see the results. If that's the issue I'm done with VF. It's been nothing but issues from the start. I'll be looking elsewhere and taking my 1k mistake to the chest.

Sorry to hear about your issues. In my case, the part of the sensor that was exposed to the exhaust flow became so brittle that it broke apart as the sensors were removed.

I can't say for certain it's the tune in your case, but considering you still have stock downpipes installed, in my opinion it's more likely the tune than the sensor just "going bad" after 300 miles.

[paulo_f80m3]

Originally Posted by ntg44

Sorry to hear about your issues. In my case, the part of the sensor that was exposed to the exhaust flow became so brittle that it broke apart as the sensors were removed.

I can't say for certain it's the tune in your case, but considering you still have stock downpipes installed, in my opinion it's more likely the tune than the sensor just "going bad" after 300 miles.

Yeah, Its so weird. I checked the voltage with ISTA and they're operating fine. Its just so odd that the heater has failed after literally 300 miles. I'm going to start digging Thursday and Friday and see what's up. It's just so deflating that I finally take her out after winter hibernation get it serviced and boom CEL.. Lol.

[paulo_f80m3]

So I'm replacing the sensor at the moment and once I removed it I noticed some condensation in the sensor. It's not fuel so that's good. I have a weird feeling that it's the low rpm cold start that's affecting this. I feel like it's not letting the condensation push out and it just sits in the sensor. Maybe I'm wrong but I'll still have to test the factory start for a couple of hundred miles and if the problem doesn't come back then that's the issue. Maybe my car just doesn't like it.

[paulo_f80m3]

600 miles later and no CEL on the stock map. I'm really leaning torwards the tune issue. Ill be contacting VF but I feel like they're not going to do much. May switch over to BM3.

[jeff@autocouture]

We have recently seen here on a few dp+ tune cars the downstream bank 1 o2 sensor faulting. We have replaced 6 of them in the past 2 months, never upstream or bank 2 downstream. Something seems to be growing into an issue..

[paulo_f80m3]

Originally Posted by jeff@autocouture

We have recently seen here on a few dp+ tune cars the downstream bank 1 o2 sensor faulting. We have replaced 6 of them in the past 2 months, never upstream or bank 2 downstream. Something seems to be growing into an issue..

It has to be some sort of tune issue.. I'm not sure. I may suck it up and run a bad sensor and CEL until emissions time and swap a good sensor when needed. Or maybe a o2 spacer could help. I just hate seeing that light on a 50k+ car lol..

[jeff@autocouture]

Originally Posted by paulo_f80m3

It has to be some sort of tune issue.. I'm not sure. I may suck it up and run a bad sensor and CEL until emissions time and swap a good sensor when needed. Or maybe a o2 spacer could help. I just hate seeing that light on a 50k+ car lol..

Tough to say, We have cars running multiple tuning company files. Always seems to be the same damn one.

[paulo_f80m3]

Originally Posted by jeff@autocouture

Tough to say, We have cars running multiple tuning company files. Always seems to be the same damn one.

2.5k miles later and no SES on my CS tune again. Knock on wood. Looks like the OEM Bosch sensor is working. I have a feeling that there may have been a widespread bad batch on the OE Bosch sensors from BMW but we'll have to see.

[Superg3]

I recently got the same code. 11k on the car, catless dp’s, mpe, have had BM3 for the last 6k. Stage 2 with cold start off for the first 4K, then CS tune with cold start on for the last 2k.

I have a oem sensor to install. Is this a easy DIY with a floor jack?

[TopJimmy]

Originally Posted by Superg3

I recently got the same code. 11k on the car, catless dp's, mpe, have had BM3 for the last 6k. Stage 2 with cold start off for the first 4K, then CS tune with cold start on for the last 2k.

I have a oem sensor to install. Is this a easy DIY with a floor jack?

It can be DIY but to do it right requires removing the exhaust and then the cat(s) to swap out the sensor. This method requires both sets of gaskets, and experience with v-band work up where it's very hard to see. I did the job using hand tools, tire blocks and jack stands, it took 10h.

[f20kills]

You have cold start off? I just got the error too and took off cold start.