Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

Ignition ON.
Verify the manifold absolute pressure sensor is within the range specified for your altitude. Refer to Altitude Versus Barometric Pressure
- If not within the specified range
  Refer to DTC P0106 (LTG) DTC P0106 (LCV)
- If within the specified range
Engine running at the operating temperature.
Verify the Long Term Fuel Trim parameter is between -10% and +10%.
- If greater than +10%
1. Ignition OFF.
2. Inspect for the conditions listed below:
  - Mass air flow (MAF) sensor signal skewed. If the Short Term Fuel Trim parameter changes greater than 20% when the MAF sensor is disconnected, refer to DTC P0101 (LTG) DTC P0101 (LCV) .
  - Fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
  - Missing, restricted, or leaking exhaust components. Refer to Symptoms - Engine Exhaust .
  - Malfunctioning fuel injectors. Refer to Fuel Injector Diagnosis .
  - Split, kinked or improperly connected vacuum hoses.
  - Insufficient fuel in the tank
  - Low fuel pressure. Refer to Fuel System Diagnosis .
  - Vacuum leaks at the intake manifold, the throttle body, and the injector O-rings.
  - Leaks in the air induction system and the air intake ducts
  - Missing air filter element
  - Cracked EVAP canister
  - Evaporative pipes obstructed or leaking
  - Leaks in the crankcase ventilation system. Refer to Crankcase Ventilation System Inspection/Diagnosis (LCV)Crankcase Ventilation System Inspection/Diagnosis (LTG) .
    - If a condition is found, repair as necessary.
    - If no condition is found, inspect the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical (LCV)Symptoms - Engine Mechanical (LTG) .
- If less than -10%
1. Ignition OFF.
2. Inspect for the conditions listed below:
  - Mass air flow (MAF) sensor signal skewed. If the Short Term Fuel Trim parameters for both banks changes greater than 20% when the MAF sensor is disconnected, refer to DTC P0101 (LTG) DTC P0101 (LCV) .
  - Fuel contamination - Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
  - Missing, restricted, or leaking exhaust components - Refer to Symptoms - Engine Exhaust .
  - Malfunctioning fuel injectors - Refer to Fuel Injector Diagnosis
  - Collapsed or restricted air intake duct
  - Excessive fuel pressure - Refer to Fuel System Diagnosis
  - Dirty or restricted air filter
  - Objects blocking the throttle body
  - Improper operation of the evaporative emissions control system
  - Excessive fuel in the crankcase. Change the engine oil as necessary.
- If a condition is found, repair as necessary.
- If no condition is found, inspect the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical (LCV)Symptoms - Engine Mechanical (LTG) .
- If between -10% and +10%
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed in the Freeze Frame/Failure Records data.
Verify DTC P0171 or P0172 is not set.
- If any of the DTCs set
  Refer to conditions listed above.
- If none of the DTCs set
All OK.