I have a 120i BJ2005 with 152,000km at the moment.
At 140,000 came a new one !! Exchange engine in (connecting rod bearing damage due to remnants of the timing chain guide rails in the oil intake.)
Old engine type N46B20 A - new N46B20 BD.
Before the replacement, the error (29F5) also occurred sporadically - the previous owner had already changed the corresponding sensor (I took over the car with 137K km).
The suspicion of loose / corroded plug connection had not been confirmed. (Have explicitly looked at both Kats and the lambda sensors visually during the engine change).
Cat 1 is for cylinder 1 + 3, cat 2 for 2 + 4.
When changing the engine, of course, new injectors, spark plugs and coils came in.
I also exchanged the LMM 2 months ago (was defective).
Exhaust route I checked - is tight. (Someone holds on to the muffler while the other looks at whether gases are escaping somewhere (idle) - error processing according to ISTA (Rheingold)
I'm slowly reaching my limit ...
The stupid thing is - occurs only sporadically and cannot really be provoked.
Does any of you have an approach where I could still look?
BTW average consumption is 9.5 / 100km - seems a bit high to me ...
According to the on-board computer, it is 7.1 (with an already increased offset which can only be set to a maximum of 12.5% - matching consumption ...)
BTW2: when cold, the engine jerks a little at low engine speeds .... but is still acceptable.
