Circuit/System Verification

WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.

Observe the DTC information with a scan tool. DTC P2177, P2179, P2187, or P2189 should not be set.
- If any other DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnosis the applicable DTC.
Ignition ON, observe the scan tool barometric pressure (BARO) sensor pressure parameter and compare the reading on the scan tool to the barometric pressure table. Refer to Altitude Versus Barometric Pressure .
- If the BARO sensor pressure is not within the range specified for your altitude, refer to DTC P2227, P2228, or P2229 .
Engine at normal operating temperature, observe the scan tool Long Term Fuel Trim parameters. The LT FT Cruise/Accel parameters should be less than 24 percent. The LT FT Idle/Decel parameters should be less than 7 percent.
- If a parameter is not within the specified range, inspect for the following conditions:
  - The heated oxygen sensor (HO2S) is installed securely and the electrical connector is not contacting the exhaust system.
  - Missing, restricted, or leaking exhaust components-Refer to Symptoms - Engine Exhaust .
  - The air intake system after the MAF sensor for vacuum leaks
  - A MAF sensor signal that is skewed-If the Short Term FT parameters for both banks changes greater than 20 percent when the MAF sensor is disconnected, refer to DTC P0101 .
  - Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/ Special Tool) and Fuel System Cleaning .
  - Splits, kinks, or improper connections at the vacuum hoses-Refer to Emission Hose Routing Diagram .
  - The fuel system is operating lean. Refer to Fuel System Diagnosis .
  - Vacuum leaks at the intake manifold or throttle body
  - Leaking crankcase ventilation system
  - The ECM grounds for being clean, tight, and in the correct locations
  - A high engine oil level condition-A high engine oil level causes oil residue to form on the MAF sensor, causing a lean indication. The MAF sensor does not need to be replaced.
  - Vacuum leaks that only affect one bank of the engine-For example, the intake manifold, the injector O-rings.
  - Lean injectors-Refer to Fuel Injector Solenoid Coil Test .
  - An engine 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.