[TassieBMW]

My 2005 E90 330i which has 313,000km (194,000 miles) has codes for both catalytic converters (29F4 and 29F5).

For a while I could clear these and it would be a month or two before they came back, but now they're coming back every day or second day after clearing.

Firstly, I'm wondering if there's any actual effect on the car other than decreased emissions efficincy? There is no emissions testing where I live so don't need to worry about that. Unsure if they're bad enough to have an effect on performance, but I assume the car would be throwing other codes if this were the case?

I'm also wondering how likely it would be that the post-cat O2 sensors are causing this, and not the cats themselves.

The car is obviously quite old and not worth a lot now so it doesn't make a lot of sense to spend heaps on new cats and the labour to fit them. The most annoying thing is having the check engine light constantly on, so I won't know if there's an actual problem with the car when I'm driving which annoys me.

Any advice from others who've dealt with this would be much appreciated.