Code Help: P0170 - Fuel Trim

[megamilam]

I just pulled a P0170-Fuel Trim Code and I'm not sure what to do:

In the past month I've changed the fuel pump relay, MAF, ECT, thermostat and the Pressure Control Line. I don't appear to have any vacuum leaks either. Before I change all of these sensors, the dealership read my fuel richness and it was as follows:

006 - Basic setting
Display group 32
System in basic setting
4.7%
15.6%

I'm not sure what this code means, or what to do. Any suggestions?

[megamilam]

I'm still having this trouble. Does anybody have any ideas?

I think it might be the O2 sensor, but I'm not sure...I think there are 4 of them? How do I know which one to change?

HELP!

[Smileybug]

There are only 2 O2 sensors, one before and one after the catalytic converter.

Did you clear the code after you did all of those things?

This as close to the code I can find on the Ross-Tech wiki (they don't have p0170 listed but they do have P0171). Might help you out. You probably want to find someone around with Vag-Com. I know there is a decent group VW owners in the Charlotte area. If you head over to NCDubs.org, you can probably find someone who can give you a hand.

16555/P0171/000369 - Fuel Trim; Bank 1: System Too Lean
Possible Causes

* Mass Air Flow Sensor (G70) defective
* Intake System Leak(s)

Possible Solutions

* Check Mass Air Flow Sensor (G70)
* Check Fuel Pressure Regulation
* Check Fuel Pump
* Check Injectors
* Check Intake System for Leaks
* Check Exhaust System for Leaks
* Check Secondary Air System for Leaks
* Check Vacuum Pipes for Leaks

[megamilam]

Thanks for your help!

I have cleared the code several times, but for some reason it keeps coming up.

I'm pretty sure that I've checked everything else on your list. Do you think O2 might be a potential cause?

[Bluestream]

Check your brake booster for leaks. Does the brake pedal go hard after a min or two or hold a vacuum over time? Sometimes you can hear a hiss when the engine is shut down, if you put an ear near the booster if it is not holding vac. This can give the code you have

[megamilam]

I just replaced the O2 sensor last night...I think it may have fixed the problem. But, I have a 40 more miles to drive before I know for sure.

I'll keep you posted.

[Bluestream]

Which O2 sensor did you replace? I doubt that is the issue, but let us know...