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2006 Chevrolet Trailblazer Question: PO171 OBSII Code keeps coming up



PDWILK, Graham, NC, January 06, 2011, 08:57

Check engine light on, PO171 Code indicates running lean. No performance problems, no change in gas mileage, not running rough, no delayed start. Replaced Oxygen Sensor bank 1, cleaned mass air flow sensor, sprayed intake manifold with carb cleaner to check for leaks (no change in idle or performance). Considering PCM reprogramming at GM dealer. Any suggestions?

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  • Answer #1

    January 06, 2011, 09:45

    I'd check fuel pressure and if all vacuum hoses are attached to the intake, no cracks on them. Also check the intake manifold for leaks with a smoke pump.
    I'd get a professional fuel injector cleaning also. Beside the MAF sensor the dirty injectors are commonly setting P0171 lean codes on GM vehicles.


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