P0172 or P0175
Allow the engine to reach operating temperature. With the engine running, observe the affected Long Term FT parameter with a scan tool. The value should be more than approximately -20 percent with the engine running at operating temperature.
⇒ If the value is not more than -20 percent, 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
? Malfunctioning fuel injectors
? Fuel contamination
? 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