E46 Fanatics Forum banner

Service Engine Light

2961 Views 3 Replies 3 Participants Last post by  Archbid
Hey everyone,

The other day, I noticed the Service Engine Light turn on on my '05 M3 Vert. It stayed for about a day and then went off, but I'm still a bit worried. I ran diagnostics on my own, after the light went away, (thru Carly BMW), and one of the faults is "00000C, Lambda probe 2 before Kat" I have a feeling this is an O2 sensor thing, but I'm not really sure. Should I just clear the code and see if the light comes back on/check the codes in a week or so to see if the fault is still there? Or do I need to take action now?

1 - 4 of 4 Posts
Suggest you get the OBDFusion App, far superior to Carly for OBDII and driveability.

The SES/CEL/MIL can come on and will turn itself off if the problem clears and has not been detected after a specified number of start cycles.

Suggest you replace the Pre-cat O2 sensors at 100k miles which is what BMW and most other manufacturers recommend as O2 sensors are "consumable" like spark plugs. I would not worry about the Post-cat O2 sensors unless there is a specific error for the Post-cat O2 sensors.

But be careful about 02 sensor codes, I never see these unless the heater circuit has failed for an O2 sensor. Usually most O2 sensors related codes are really an indicator that the fuel mixture is out of range.

OBDFusion with Freeze Frame data from a Diagnostic Report is your friend. You might be able to use the current interface you are using for Carly with OBDFusion, just try it and see what happens. Best to keep the interface in the car and RUN and SAVE a Diagnostic Report while the SES/CEL/MIL is on.

If you have a smart phone or tablet, get an OBDII App and interface so you can read the codes along with Live/Realtime or Freeze Frame data then you will know exactly what is going on with the engine fuel management system.

The OBDFusion App and proper VeePeak interface from Amazon are less than $40 for both for iProducts, less than $20 for both for Android.

OBDFusion for Android is $4.99 from the Google Play Store.

For Android this lower cost standard Bluetooth interface in the link below works well, but DO NOT try to use this with iProducts.


OBDFusion, for the iProducts it is $9.99 from the Apple App Store.

For iProducts you NEED a LE Bluetooth adapter which are more expensive. VeePeak now offers a LE Bluetooth interface that is compatible with OBDFusion in the link below. While people have used the Wifi adapter, I would HIGHLY recommend NOT using Wifi with iProducts, brings a lot of baggage and stability issues.

See less See more
Thank you for the detailed response!! This helps a lot. The light hasn***8217;t come on since, so I think I***8217;m fine but as you said will probably replace pre cat o2s at some point in near future anyway.
Thank you for the detailed response!! This helps a lot. The light hasn't come on since, so I think I'm fine but as you said will probably replace pre cat o2s at some point in near future anyway.
You may have pending codes, and you will need the OBDFusion app soon enough anyway. Get it and check your long term fuel trims. Also, replace the sensors as JFOJ said if you are over 100k. Not hard, just don't mix up the wires ;)
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.