2006 Trailblazer Check Engine Light - code PO171

cpick13
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Joined: Fri Jan 11, 2013 9:55 am

2006 Trailblazer Check Engine Light - code PO171

Unread post by cpick13 » Fri Jan 11, 2013 10:01 am

4.2 L engine has no running issues. Light comes on for a couple of days then goes off for a day or two, then comes back on. Usually comes back on when in stop and go traffic. Code PO171- System Too Lean Bank 1. Truck has 245,000 miles.

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TerryAuto
Posts: 316
Joined: Fri Dec 11, 2009 8:48 pm

Re: 2006 Trailblazer Check Engine Light - code PO171

Unread post by TerryAuto » Fri Jan 11, 2013 10:34 pm

P0171 lean is usually caused by a vacuum leak. There is a common problem on the 4.2L described here...
GM 4.2L P0171 Lean Code.
That will usually give you some driveablilty problems though.

If you do not find a vacuum leak, then you may be getting some bad gas. High alcohol will give a lean code depending on the percentage and driving conditions. You would need a fuel composition test to determine that.

Another possibility is just a bad oxygen sensor.

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