[Elmantukas]

Hello to you all lovely people! Hope you are all doing absolutely well because im about to finish pulling the last bit of my hair out, this car is absolutely driving me crazy, and i have lost all hope hence why im here, the car is. 325i with the N53 engine from 2010. It all started with the 29F5 code which is catalytic converter bank 2 efficiency bellow threshold, and also, after a warm engine shut down and restarted after 2-3 hours, it cold starts, holds about 1K rpm and then very quickly starts dropping until it starts shaking on 600rpm, as if the car starts reading the o2 sensors too early, few revs and the idle is stable, never happens on the morning start, so couldn't be injectors, which are index 11. Now im getting a 3104 code constantly, rough running in stratified charge mode, changed spark plugs, changed nox sensor, all adapted all nice, no change. Anither code is 2A27, this has something to do with cat efficiency in stratified charge mode. Could this be the downstreams reading wrongly? Could it be the upstreams being dodgy? There is absolutely no smell out of exhaust, especially no rotten eggs smell, pulled o2 sensors out cats seem whiteish but all intact and nice, i just dont know anymore.. has anyone have any idea? Also after i delete the codes, in the motorway it feels like the car just stutters a few times under load, but could be just the bad roads we have here, especially M25 haha. Anyway thanks for your time and i hope you could understand me well, big ben no speak london sometimes.

Edit, car is on 128k miles, surely cant be the cat dieing, exhaust is also not sooty and just usually dripping watter

[E92_William]

It is worth a try to change the downstream sensor. It's not gonna be the first time one has gone bad and shown the catalytic converters being bad while the sensor is the one with the issue. If the bank 1 and 2 are the same sensor then maybe you could swap around and see what happens while swapping the connectors too of course

[0l0dom0l0]

Have you checked to see if you are running the latest DME software? If not update it.

[Dormermike]

I get that stutter on the motorway occasionally. I posted on here and a few agreed it might be nox being cleaned out. I am not so sure, as it feels like a misfire. For yours i'd suspect o2 sensors too, but think you need a proper scope to test them? Must admit i'm very close to exiting my n53 after nearly 7 years of absolute reliability - feel a big bill is on the way!!