[Krysiaman]

Hi! 
I recently have two 116i with N45 engine (ME9). Both had error 2C55 - O2 sensor ageing. In both cases we replaced O2 sensors with brand new NGK sensors (same as OEM) and this error comes again after 100km - 200km. There is no any other errors, engine runs fine. 


Anyone had this problem? If I have two same cases in similar cars I belive that this is pretty common problem

[willisodhiambo]

What mileage? Most likely its CAT aging, not O2 sensor!

[Krysiaman]

One is 2006 176 410km and second is 2005 176 737km, almost identical cases I've seen a lot of N42, N45, N46 with clogged cat but they threw different codes, mostly related to cat

[willisodhiambo]

What does ista suggest in the repair procedure? At that mileage I can bet it is inefficient CATs.

[Krysiaman]

I didn't checked what it suggest in test plan, don't ask me why. I just forgot   I consider inefficient cats but I want to check few things before removing cats. I wanted to update DME but I couldn't - see  attachment. Same in ISTA/P...