Circuit/System Verification
WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition - On / Vehicle - In Service Mode
- Verify there are no DTCs set related to the following component/system:
- B52 Heated Oxygen Sensor
- B65 Manifold Absolute Pressure and Intake Air Temperature Sensor
- B75 Mass Airflow Sensor
- B150 Fuel Tank Pressure Sensor
- Q12 Evaporative Emission Canister Purge Solenoid Valve
- Q17 Fuel Injector
- Q38 Throttle Body
- Engine Misfire
- Secondary Air Injection System
- If a related DTC is set
- Go to next step: If a related DTC is not set
- Verify the scan tool parameter: Manifold Absolute Pressure Sensor = The value should be within the range listed in the table: Altitude Versus Barometric Pressure
- If not in the specified range
- Go to next step: If in the specified range
- Engine - Idling
- Disconnect the electrical connector: B75 Mass Airflow Sensor
Verify the scan tool parameter: Long Term Fuel Trim = The parameter value should not change - Greater than 20%
- If the change is 20% or greater
- Go to next step: If the change is less than 20%
- Ignition/Vehicle & All vehicle systems - Off
- Connect the electrical connector: B75 Mass Airflow Sensor
- Engine - Idling
- Verify the scan tool parameter: Long Term Fuel Trim = Less than 10%
- If 10% or greater
Refer to: Circuit/System Testing - P0171
- Go to next step: If less than 10%
- If 10% or greater
- Verify the scan tool parameter: Long Term Fuel Trim = Greater than -10%
- If -10% or less
Refer to: Circuit/System Testing - P0172
- Go to next step: If greater than -10%
- If -10% or less
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Verify the DTC does not set.
- If the DTC sets
Refer to: Circuit/System Testing
- Go to next step: If the DTC does not set
- If the DTC sets
- All OK.