Circuit/System Verification
- Engine running, observe the DTC information with a scan tool. Verify that other DTCs are not set.
- Ignition ON, observe the scan tool manifold absolute pressure (MAP) sensor pressure parameter and compare the reading on the scan tool to the barometric pressure table. Refer to Altitude Versus Barometric Pressure .
- Engine running, observe the scan tool TP sensor percentage parameter. The reading should be less than 10 percent.
- Observe the scan tool HO2S sensor voltage parameter. The reading should fluctuate within 200-800 mV.
- Engine at normal operating temperature, observe the scan tool Long Term FT parameter. The reading should be between -5 to +5 percent.
- If not within the specified range, verify none of the following conditions exist:
- Fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Splits, kinks, or improper connections at the vacuum hoses.
- The fuel system is operating lean or rich. Refer to Fuel System Diagnosis .
- The fuel injectors are operating lean or rich. Refer to Fuel Injector Solenoid Coil Test .
- Missing, restricted, or leaking exhaust components. Refer to Symptoms - Engine Exhaust
.
- Vacuum leaks at the intake manifold, throttle body, and injector O-rings - P0171.
- Leaking crankcase ventilation system - P0171.
- The air intake duct for being collapsed or restricted possibly by a restricted air filter - P0172.
- Leaking fuel pressure regulator. Inspect for evidence of fuel in the vacuum line-Refer to Fuel System Diagnosis - P0172.
- Excessive fuel in the crankcase - P0172.
- The incorrect operation of the evaporative emissions control system - P0172.
- If all conditions test normal, test the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical
.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.