P0172 or P0175
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Allow the engine to reach operating temperature. With the engine running, observe the affected Long Term FT parameter with a scan tool. The reading should be between -19 and 0 percent.
- If not within the specified range, inspect for the following:
- With the engine idling and the transmission in the Park or Neutral position, observe the manifold absolute pressure (MAP) sensor parameter. The MAP sensor parameter should be between 19-42 kPa.
- Refer to DTC P0106 if the MAP sensor parameter is not between 19-42 kPa.
- With the engine idling, observe the mass air flow (MAF) sensor parameter. The MAF sensor parameter should be within 2-6 g/s at idle.
- Refer to DTC P0101 or P1101 or DTC P0102 or P0103 if the MAF sensor parameter is not within 2-6 g/s at idle.
- Vacuum hoses for splits, kinks, and improper connections
- The air intake duct for being collapsed or restricted
- The air filter for being dirty or restricted
- Objects blocking the throttle body
- Excessive fuel in the crankcase due to leaking fuel injectors
- The evaporative emissions control system for improper operation
- Excessive fuel pressure-Refer to Fuel System Diagnosis (w/o FPCM) or Fuel System Diagnosis (w/FPCM) .
- Malfunctioning fuel injectors-Refer to Fuel System Diagnosis (w/o FPCM) or Fuel System Diagnosis (w/FPCM) .
- Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) .
- The HO2S for improper installation and for electrical wires or connectors that may have contacted the exhaust system
- The HO2S signal circuit shorted to voltage