Circuit/System Testing

IMPORTANT: You must perform the Circuit/System Verification before proceeding with 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 -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.
  - If the MAP sensor parameter is not between 19-42 kPa, refer to DTC P0106, P0107, or P0108 .
- 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 P0100, P0101, 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 or MAF Sensor
- 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
- Missing, loose, or leaking exhaust components from the HO2S forward
- The HO2S for improper installation and for electrical wires or connectors that may have suffered corrosion, water intrusion, or contacted the exhaust system
- Incorrect terminal tension at electrical connectors
- Loose, corroded, or mislocated electrical ground connections
- A restricted exhaust system
- The HO2S signal circuit shorted to voltage
- Malfunctioning engine components