[AsianBill]

Hey guys so I went to do a pull and scanned the car got this code 128901 I believe this is the primary o2 sensor correct? Just want to make sure I have the correct understanding before throwing a part at a problem. Screenshot below from bm3


Also took a log to see if anything odd is coming up. Got one knock event but I'm assuming bad gas since I had it happen before. Car is EWG, drop in intake/Catless/Race IC/Turbosmart BOV/Turbo inlet are the mods on BM3 multimap stage 2 running 93 on the 91 map

Link is here: https://www.bootmod3.net/log?id=6100...90c64360f53c81

Car feels good at the moment.

Any advice is appreciated

[thejeremyman9]

Yes that is the primary/upstream o2 sensor (before cat). And yes you have a knock in the log and in addition your timing looks pretty bad even after the knock, at higher RPM. I would log again on a fresh tank of gas.

[MTTH]

I just got this same code, 128901. The car has 14K miles on it & is stock other than an MST intake & one resonator delete. I filled up with 93 Oct & 1 gallon of e85 2 days ago if that makes a difference.

Not sure what would cause this code. I cleared it but I haven't driven it to see if it comes back.

[thejeremyman9]

Originally Posted by MTTH

I just got this same code, 128901. The car has 14K miles on it & is stock other than an MST intake & one resonator delete. I filled up with 93 Oct & 1 gallon of e85 2 days ago if that makes a difference.

Not sure what would cause this code. I cleared it but I haven't driven it to see if it comes back.

Do you have a N55? Asking cause you said "one resonator" and your profile says 440

[BMWILUVU]

Originally Posted by MTTH

I just got this same code, 128901. The car has 14K miles on it & is stock other than an MST intake & one resonator delete. I filled up with 93 Oct & 1 gallon of e85 2 days ago if that makes a difference.

Not sure what would cause this code. I cleared it but I haven't driven it to see if it comes back.

e85 is probably fouling your upstream. If it comes back, you may need to replace your upstream O2 sensor.

[n55david]

Originally Posted by BMWILUVU

e85 is probably fouling your upstream. If it comes back, you may need to replace your upstream O2 sensor.

E85 doesn't normally do that

[MTTH]

Originally Posted by thejeremyman9

Do you have a N55? Asking cause you said "one resonator" and your profile says 440

Sorry, I’m just seeing this as I never got a notification of any responses. Funny enough, the code just came back and I started researching again and saw I commented here. No, I don’t have an N55, didn’t realize this was N55 section when I first commented, sorry.