JQuala

So I have code p0036 bank 1 o2 sensor 2. Short circuit it is reading extremely low 0.3mv or so. Since it's sensor 2 and is plugged in via extension with EC tune, so it's tuned off...why has it affected my fuel trims. I thought that's sensor 1's job. Sensor 2 just measures hydrocarbons and other exhaust fumes?

Merc63

I have booth those codes, thoufhtbthey don't affect anything either. Why do you say that about fuel trims?

hachiroku

if the EC tune has disabled your rear sensors...you shouldn't be receiving any code i thought?

that code means your sensor is dead...or extension is causing the heater circuit to fail.

shouldn't affect your fuel trims. they are there to notify if your catalytic converters are not functioning correctly.

JQuala

My LTFT spiked back up to 25% from >10% I realized on dashcommand and torque the LTFT and STFT are weird. I hooked it up to both my moms c350 and sisters c350 and they both read around 7-10% ltft. Unless all of our cars have vaccum leaks I think it's either my obdIi or the app.

Also, I have v7 EC tune but my dashcommand can read the voltage on both rear o2s but nothing for the front pid

chrisridebike8

so this sucks. I have been gone less than a month on deployment. my parents have my car. the car has EC v6 tune with catless ARH LTHs with the o2 extensions. It popped a p0036 code which doesnt make sense as stated above. the tune should have shut the sensors off. they are in San Diego, so they can always take the car to a shop I trust down the road, but not being there makes it hard for me to tell them what to do. Any resolution to this problem? this seems to be the only thread with this code.

roadkillrob

I don't believe any tune shuts off the sensors as the engine needs a reading from them, both pre and post cat is my understanding. They just disable the monitor channel so that it always says not ready and won't throw a check engine light for emissions, but the sensor is still functioning and if it fails it will throw a code.

I have a 335i also and the 335i guys were running 02 simulators to basically take the reading from the post cat sensors and always tell the ECU that they were within spec and it actually caused issues and the manufacture stated they should not be run all the time as the car still needs to know what is going on with the post 02 sensors as they are doing more than just emission readings.

I think you need to replace your failed sensor regardless of the tune.

chrisridebike8

Ok. Maybe I'll have them replace the downstream sensors. I know people like BLKROKT don't even have them plugged in. Or maybe his are plugged in and not installed in the exhaust. He has dual wideband O2 sensors in their place. Thanks.

roadkillrob

I think in general it doesn't cause much of an issue but my understanding is most cars use them to help calibrate the primaries, so if something goes amiss with a primary and the secondary is having issues, then odd things can occur - not saying that is 100% the case with this car but has been my experience with other cars.

on the N54 forum, a few people had some weird issues with fuel trims when the primaries and secondaries had calibration issues due to the secondaries failing, but some people never seem to have an issue even with the secondaries removed, so I think it is a function of your primary running out of spec and not having the secondary to help calibrate it. If your primaries are working perfectly, secondary may never be needed.

chrisridebike8

strange. primaries are 5k miles old.