Check Engine Light - P0171 Fuel System Lean

[dcs577]

The Check Engine Light turned on in my 2006 AWD Pontiac Vibe just yesterday...Thanksgiving Day. Coinciding with the light were a few performance issues. I noticed some slight hesitation in the engine as well as some jerky motions in the steering wheel. Autozone told me it was a P0171 code which means the fuel system is too lean....possibly due to a MAF sensor, Oxygen Sensor, intake leak, or any other variety of problems. Today, I drove an hour to get home from my girlfriend's house and near the end of that drive, I topped off my half full gas tank. Sometime shortly after that, the CEL turned off. However, the performance issues remain. I inspected the MAF sensor and cleaned it. It looked normal as best as I could tell. I plan to inspect the spark plugs tomorrow.

Any ideas as to why the CEL would turn off even though the performance issues remain? Should I avoid driving it any lengthy distance until I can get it repaired? I made an appointment to have it diagnosed. Any other ideas as to a probable cause for the issue including the odd steering wheel motions?

Any help would be much appreciated. Thanks.

[lannvouivre]

It's most likely a vacuum leak. When the engine is running and you have the hood open, do you hear hissing? If so, follow it by ear.

If that doesn't work, get a can of carb cleaner and spray it in various areas: the fuel injectors where they spray into the intake ports, the intake manifold to head surface, around the throttle body, and on the PCV and breather hoses as well as any other vacuum lines.

[Raven]

A leaky intake manifold gasket is common, there's a recent thread about it. There's an improved gasket available from Toyota which will last longer. Just tell the Toyota dealer you have an AWD Matrix.
I've been driving mine with an intermittent PO171 code for 2 or 3 years but have no other driveability issues.

I'm not suggesting you do the same as somebody will jump down my throat, just saying.

[cptnsolo77]

I have had that code twice since I owned the Vibe. Check you gas cap & reset. It may be that simple

[vibrologist]

I have had that code twice since I owned the Vibe. Check you gas cap & reset. It may be that simple

Shouldn't that result in an Evap code rather than a lean code?

[cptnsolo77]

Good question ! I had to double check & found this. http://www.agcoauto.com/content/news/p2_articleid/151" onclick="window.open(this.href);return false;. The gas cap IS part of the evap system. So yeah it makes sense that it will trigger a evap code. I stand corrected. I swear it was a PO171

[Salsa Guy]

Don't replace the O2 sensor or MAF. It's a Vac leak more than likely.