P0153 P0174 codes (solved: clogged CATS)

Hello everybody I am reaching out to the community for some help on codes that are on and off on my 2004 330ci with 269,000 miles. I have been dealing with especially P0153 and P0174 on and off again for about a year and a half now. Sometimes I get also a P0302 engine 2 misfire code together with the P0153 but that hasn't happened since this last spring.

I have tried look this up to figure what could be causing these codes, have replaced a few parts already and took it to a shop which specializes in German cars which I am at the point the common solutions have not fixed it. I have gotten the OBD fusion app and followed the link to download the three logs if somebody could please read them and help with a direction with the issue. I have it attached to this post.

Just wanted to let you guys know of parts that I did change already in order so there is no misunderstanding. The very first time I noticed I had an issue with the car it was running rough at times which popped the P0302 code. Since I had last bought coils and packs from FCP Euro, I bought new ones and did a lifetime return. After the next day I noticed the P0153 code pending. Since the car at the time was over 250,000 miles on the original O2 sensors, I replaced both banks Pre sensors with new Bosch and at a later date I did the post O2 sensors with new Bosch. I took it as so many miles maybe it is starting to loose its life expectance as I have read in the forum that they are technically good up to 100,000 miles which I already pretty much double that. Not 100% sure if I buy that now.

So basically after the O2 sensors were replaced on and off again I mostly got the P0174 code either pending or stored and the P0153 either pending or stored. After the O2 sensors being replaced I bought a smoke machine off Amazon and smoke tested the car probably about three different times and could not find any vacuum leaks as reading up on the cause of P0153 code could be a possible vacuum leak. At this point I was coming close for inspection and needed to get the car to pass. I did have a few years back a P0174 code and after replacing my MASS Air flow sensor it cleared the issue at the time. So since I bought from FCP Euro, I did a return for a new one. Cleared the codes and passed inspection with no issue. I was wondering if it did the job so for about 2 months I had no pending or stored codes. I was like great it is fixed once and for all.

At the beginning of this month I started getting once again the P0153 code. Two weeks later my light came on and I said let me take the car to get it checked out as I have been busy with work and not finding enough time to sit and troubleshoot the issue correctly. That is when I took it to the shop. I explained everything the car would do and what parts I had already replaced on the car. They assumed at the time it is probably a vacuum leak. The following day they contacted me and said they could not either find a vacuum leak and recommended to replace again my O2 sensors at $1175. I was not 100% sure if it was was for all 4 or just the 2 sensors. I told them no thanks as I already once again told them I replaced them in the beginning. When I went the next day to pick the car up I spoke to actually the tech who worked on my car and he was not aware I had changed the O2 sensors as the guy on the phone just writes the cars up and didn't pass the info. The tech at the time thinking what issues I had and based on mileage then recommends I replace my fuel injectors. Didn't ask for a price as I was ok.

It was at this point I decided to get the OBD fusion app and do the downloads that hopefully somebody could read the logs and give me some guidance. Or hopefully fix the problem once and for all.

Sorry for the long post as I wanted to make it known what the car was doing and what I already replaced. This car is basically my daily driver to and from work and I had this car since new over 19 years now. I enjoy driving it as it is fun to drive. Especially a manual.