Circuit/System Testing

Allow the engine to reach operating temperature. With the engine running, observe the Long Term FT parameter with a scan tool. The value should be more than approximately -25 percent with the engine running at operating temperature.

• If the value is not more than -25 percent, inspect for the following:

• With the ignition ON and the engine OFF, observe the BARO sensor parameter. The BARO sensor should be within the range specified for your altitude. Refer to Altitude Versus Barometric Pressure .
  • If the BARO sensor does not indicate the correct barometric pressure, refer to DTC P2227, P2228, or P2229 .
• With the engine idling, observe the mass air flow (MAF) sensor parameter. The MAF sensor parameter should be between 2-6 g/s at idle.
  • If the MAF sensor parameter is not between 2-6 g/s at idle, refer to DTC P0101 or P1101  or DTC P0102 or P0103 .
• 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 .
• Malfunctioning fuel injectors-Refer to Fuel Injector Diagnosis .
• Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• 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