320i (N43) O2 sensor error codes with EML

wrongmark · 07-08-2021, 10:07 AM

Due to working from home for the past 16+ months, the car sits for extended periods of time on my driveway. I recently used it for a fairly long drive (4 hours round trip) and on the way home the EML came on and stayed on. The car seemed to drive fine so no limp mode.

It's sometimes a little rough on cold start (although this might be normal) and I've been thinking that two of the fuel injectors are still originals (I replaced the other two a few years ago) and might be due for replacement soon.

The error codes were:
2C2D - lambda probe before catalyst, sheer test - signal or value above threshold
2C3D - lambda probe in front of catalyst, line fault - No signal or value
2C7E - lambda probe after catalyst, trim control - signal or value above threshold
2C7F - lambda probe after catalyst 2, trim control - signal or value below threshold

After a seach on the forums, I've not seen this combination of error codes apart from where people are messing about with JB4s etc.

My understanding is that there are three lambda/O2 sensors on this car (might be wrong?). Two were replaced 4 years ago with Bosch at 70k miles (now on 98k).

I know that lambda/O2 sensor errors don't always mean that they need replacing (i.e. could be injectors overfueling/leaking), so thought I'd ask opinions here of what to try first?

wrongmark · 08-23-2021, 11:15 PM

Did a bit of research and tested the wiring with a multimeter from the O2 sensor plugs back to the DME plug. All appears to be ok, assuming that 2KOhms on the orange wires is normal. Cleaned the plugs and the error hasn’t come back yet (although the wife said the EML had come back, causing me to purchase a new O2 sensor which I haven’t fitted yet, turns out it hadn’t ).

07-08-2021, 10:07 AM	#1
wrongmark Second Lieutenant 98 Rep 256 Posts Drives: E90 320i, F31 328i Join Date: Feb 2016 Location: South Yorkshire iTrader: (0)	320i (N43) O2 sensor error codes with EML Due to working from home for the past 16+ months, the car sits for extended periods of time on my driveway. I recently used it for a fairly long drive (4 hours round trip) and on the way home the EML came on and stayed on. The car seemed to drive fine so no limp mode. It's sometimes a little rough on cold start (although this might be normal) and I've been thinking that two of the fuel injectors are still originals (I replaced the other two a few years ago) and might be due for replacement soon. The error codes were: 2C2D - lambda probe before catalyst, sheer test - signal or value above threshold 2C3D - lambda probe in front of catalyst, line fault - No signal or value 2C7E - lambda probe after catalyst, trim control - signal or value above threshold 2C7F - lambda probe after catalyst 2, trim control - signal or value below threshold After a seach on the forums, I've not seen this combination of error codes apart from where people are messing about with JB4s etc. My understanding is that there are three lambda/O2 sensors on this car (might be wrong?). Two were replaced 4 years ago with Bosch at 70k miles (now on 98k). I know that lambda/O2 sensor errors don't always mean that they need replacing (i.e. could be injectors overfueling/leaking), so thought I'd ask opinions here of what to try first?
	Appreciate 0 Tweet Quote

08-23-2021, 11:15 PM	#2
wrongmark Second Lieutenant 98 Rep 256 Posts Drives: E90 320i, F31 328i Join Date: Feb 2016 Location: South Yorkshire iTrader: (0)	Did a bit of research and tested the wiring with a multimeter from the O2 sensor plugs back to the DME plug. All appears to be ok, assuming that 2KOhms on the orange wires is normal. Cleaned the plugs and the error hasn’t come back yet (although the wife said the EML had come back, causing me to purchase a new O2 sensor which I haven’t fitted yet, turns out it hadn’t ).
	Appreciate 0 Quote