BMW 540i Fault codes

[DaleM]

Fault Code 1B, 23, 12

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I just joined the Bimmerwerkz and have a 1998 540i

On the way home today the check engine light came on. I checked the codes and they are 1B "Fuel trim, QL additive, Cyl 1-4", 23 "Fuel trim, QL additive, Cyl 5-8", and 12 "PreCat O2 Sensor Cyl 5-8". I cleared the codes and they are gone for now.

Both PreCat O2 sensors were replaced and have a little over 1000 mile on them so I do not think they are the problem. The car is running great with no idle problems.

Does anyone have any idea what else I can check or what the problem may be when and if the error returns.

Thanks, Dale

[marti5]

Drive it for about a week then see if the codes return, if they do then there is a problem, if not all is fine, I have codes pop up esp o2 as the wife poddles around town all week as soon as I take it out for a good thrashlng all is fine the 02 just gets sooted up, as for the other codes they may have been there along time and didnt get erased when the fault was fixed.

[Jared@EACTuning]

Did you do a battery pull when you replaced your O2s so your car would reset?

[DaleM]

I was in stop and go traffic for quite a while when the light came on so maybe that was the problem. I will get it out for a long drive tomorrow and see how it goes.

Yes the battery was disconnected when I replaced them. At the same time I also replaced the Ignition switch. When I reconnected the battery I checked the fault codes and cleared everything. So I know prior to this error there were no fault codes in the system.

[marti5]

The check eng light will come on commonly for: cam sensor/crank sensor/MAF and o2, I took my MAF out the other day whilst it was running and it came on. Turned key on off twice,still on, so plugged in carsoft 6.5, reset DME adaptions and cleared all errors off it went, whilst running on live data. If you have a laptop carsoft 6.5 is invaluable must have if you own a BMW.