[bogdan18493134]

Hi everyone!

A month ago, I bought an E92 325i with the N52B25 engine, and I've noticed the engine idles a bit rough. At idle, there's a noticeable vibration from the engine, and the RPM fluctuates slowly between approximately 660-750. I connected ISTA to the car and retrieved the following fault codes:

• 0029F4: Catalytic converter conversion
• 0029F5: Catalytic converter conversion 2
• 002D06: Air-mass system

Based on my research, these codes indicate the car is running rich. The exhaust is somewhat black, and there's a noticeable gasoline smell from the back. Here are the voltage readings from the O2 sensors:

• Bank 1 before cat: 2.03V
• Bank 1 after cat: 0.75V
• Bank 2 before cat: 1.99V
• Bank 2 after cat: 0.74V

From what I understand, the normal voltage after the catalytic converter should be around 0.5V, and the readings I have suggest the car is indeed running rich.

Additionally, when I turn the steering wheel while the car is stopped, the RPM fluctuates and sometimes jumps to around 1000 RPM before dropping. I assume this is the car's way of preventing the engine from stalling, but I’ve seen similar cars with the same engine that don’t exhibit this issue.

So far, I suspect a faulty MAF sensor, an issue with the MAF sensor cable, or potentially a problem with the CCV, especially since the car is consuming more oil than normal. Is there a way to test the MAF sensor?

Any advice or suggestions would be greatly appreciated!

[mictang]

29F4 29F5 can be just the CATs are bad, especially if you are burning a lot of oil. The codes themselves are for low CAT efficiency, you would get them if you are running headers/straight pipes.

For CATs to cause idle issues, they are usually plugged from oil residues.

You can look at MAF sensor live data and see if it changes with engine load, idle is 20 something (can't remember to clearly) and goes up with engine load.