Circuit/System Verification

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. 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 system/component:
- B26 Crankshaft Position Sensor
- B34 Engine Coolant Temperature Sensor
- B52 Heated Oxygen Sensor
- B66 Intake Air Temperature Sensor
- B74 Manifold Absolute Pressure Sensor
- B75C Multifunction Intake Air Sensor
- Q17 Fuel Injector
- Q38 Throttle Body
- Engine Misfire
- Fuel Trim System
- If a related DTC is set
  Refer to: Diagnostic Trouble Code (DTC) List - Vehicle
- Go to next step: If a related DTC is not set
Verify the condition does not exist:
- Air Cleaner Element - Dirty/Water intrusion/Visible Damage
- Intake Air Duct - Loose/Poor Connection/Visible Damage
- Intake Manifold - Leaking
- Positive Crankcase Ventilation System - Dirty/Poor Connection/Restricted - Refer to: Crankcase Ventilation System Inspection/Diagnosis
- Vacuum Hoses - Incorrect connection/Kinked/Leaking/Restricted
- If a condition exists
  Repair or replace as necessary.
- Go to next step: If no condition exists
Verify a condition does not exist with the component: Exhaust System
- Leaking - Refer to: Exhaust Leakage
- Loose Clamps
- Missing components
- Restrictions - Refer to: Restricted Exhaust
- Visible Damage
- If a condition exists
  Repair or replace as necessary.
- Go to next step: If no condition exists
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 DTC P1400 is not set.
- If the DTC sets
  Refer to: Symptoms - Engine Mechanical
- Go to next step: If no DTC is set
All OK.