What could these codes mean?

[tliartis]

All,

I have a 2015 650 GC. 84k miles.About two months ago my check engine light came on and i got the below codes:

P0175- System too rich bank 2
P0430-Catalyst System Efficiency below threshold Bank 2
P0420- Catalyst System Efficiency below threshold Bank 1

Indy shop said the codes showed both cats neeses replaced. Suggested i go to dealer and see if they would cover it since it was just out of warranty. The SA who says he used to work in the garage told me it was cats when I told him the codes and he quoted me like 15k to replace them without even looking at the car.

After this i went on a trip, 3 hours each way and the light went off. The cat codes disappeared and I was just getting the system too rich for the past month and a half.

Yesterday the check in light came back on and when I scanned it it showed system too rich and now cat bank 2 only.

Today the light went off and now is just showing system too rich bank 2 again.

Has anyone dealt with anything like this? Could it just be sensors. If it happens to be both cats, it seems a lot cheaper to go catless and code the check engine light off with a tune. I'm well out of warranty and there is no emissions in SC. I'm thinking to let two Indy shops look at it and go from there.

I appreciate any help!

[Opie55]

Those look to be codes from a generic OBDII scanner? If I'm correct, has anyone scanned it with a scanner that reads BMW codes? Anyway, it is unlikely both cats would fail at once. Second, failed cats are not the only cause of those codes. Could be bad fuel injectors or bad O2 sensors. If a shop just hears a code number and says you need two new cats I would not go back to that shop.

[TGrits10]

84k is very early for cats to wear out, but on the other hand running rich accelerates cat wear so, with the rich code...plausible. I want to know why you're getting the rich code, most common cause of running rich as miles accumulate is O2 sensors wearing out, but if you're not getting a code for a bad sensor...maybe it's not yet worn enough to throw a code, but worn enough to cause a rich condition? 84k is also kinda early for O2 sensors to wear out. If there's something else upstream causing a rich condition, it could throw off the O2 sensor and cat readings and make the car think they're bad? Or it could cause premature wear on those components? I'm not qualified to analyze the various readings one can pull up, but if anything the bad cats are a symptom, not the disease.

[tliartis]

Originally Posted by Opie55

Those look to be codes from a generic OBDII scanner? If I'm correct, has anyone scanned it with a scanner that reads BMW codes? Anyway, it is unlikely both cats would fail at once. Second, failed cats are not the only cause of those codes. Could be bad fuel injectors or bad O2 sensors. If a shop just hears a code number and says you need two new cats I would not go back to that shop.

They said they scanned in and did a once over checking for anything like leaks and stuff and said it was the cat converters and sent me to the dealership. Dealership just gave me a quote and said they would "save me time" because 99% of the time the codes I have are for new cat converters.

Going to try the first Indy one more time and another to get opinions. The first ahope didn't charge me to check it and have generally been helpful so far so I want to give them another chance

[Kamate]

Originally Posted by Opie55

Those look to be codes from a generic OBDII scanner? If I'm correct, has anyone scanned it with a scanner that reads BMW codes? Anyway, it is unlikely both cats would fail at once. Second, failed cats are not the only cause of those codes. Could be bad fuel injectors or bad O2 sensors. If a shop just hears a code number and says you need two new cats I would not go back to that shop.

I agreed, most likely the rich condition causing the cat to not clean up the left over gasses fast enough. Therefore you get the cat inefficiency code. If you keep driving without fixing the root of the problem the you will damage your cat. Fix the rich condition first, not the cat.