2001 996 TT Fault Codes P0171 & P0174 Lean Banks 1 & 2

[jgood]

I have a 2001 tiptronic car with larger turbos, exhaust, flash. After a drive today, a CEL came on and its codes P0171 & P0174. Banks 1 & 2 are too lean. I have no idea why this occured. It happened after letting the car idle for about 5 min after a good, hard drive. Any help would be appreciated.

[Loren]

:welcome:

P0171 Oxygen Sensing Adaptation, Idle Range, Bank 1 – Above Limit

P0174 Oxygen Sensing Adaptation, Idle Range, Bank 2 – Above Limit

Possible fault cause

- Incorrect signal from MAF sensor

- Intake air system leaking

- Fuel pressure too low

- Volume supply of fuel pump too low

- Fuel injectors fouled

- PCV valve leaks

- Cap of oil filler neck not closed correctly or seal is damaged

[jgood]

Thanks, Loren. This code did occur after allowing the car to idle for 5-7 mins after driving, Weather was warm, about 70 but no humidity. (NY). Any easy way for me to further investigate this? I have a simple code reader. Do I need Durametics? After clearing the code, the car seems to be running fine. However, I do have some hesitations at cold idle and part (or very lite) throttle and believe this is normal for a flashed ECU. However, this code has never occured and it does worry me. Is there an easy way to further diagnose this issue?

[Loren]

See if they comes back.

If they do, then check the list of probable causes.

[jabast09]

On 9/20/2009 at 9:15 AM, Loren said:

:welcome:

P0171 Oxygen Sensing Adaptation, Idle Range, Bank 1 – Above Limit

P0174 Oxygen Sensing Adaptation, Idle Range, Bank 2 – Above Limit

Possible fault cause

- Incorrect signal from MAF sensor

- Intake air system leaking

- Fuel pressure too low

- Volume supply of fuel pump too low

- Fuel injectors fouled

- PCV valve leaks

- Cap of oil filler neck not closed correctly or seal is damaged

Loren, thank you for this post. I actually started with checking the "cap of oil filler neck"  and that was the issue! You've saved me lots of time and $$$$! thank you again!