2003 Chevy Truck diagnostic trouble codes

2003 CHEVROLET TRUCK

80,235 MILES • V8 • 4WD • AUTOMATIC

TWELVE POINT

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I have a 2003 silverado 5.3 liter 1500. Two codes PO171 and PO174 system too lean banks 1 and 2. I cleaned the MAF sensor and replaced the fuel filter and the air filter. Cleared the codes and now they're back a few days later. I was wondering what the fuel pressure should be at and what else shoud I check besides for vacuum leaks or manifold leaks?

Dec 4, 2008 at 11:41 PM

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RASMATAZ

AUTOMOTIVE REPAIR CONTRIBUTOR
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P0171/P0174

A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

Dec 4, 2008 at 11:56 PM