Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
- Ignition ON, verify the scan tool hood position parameter displays Open.
- If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
- Inspect the air intake system for the following:
- Damage, restriction, or modification
- Dirty or deteriorating air filter element
- Crankcase ventilation system for correct operation-Refer to Crankcase Ventilation System Inspection/Diagnosis .
- Water intrusion
- Vacuum leak and other un-metered air downstream of the mass air flow (MAF) sensor
- Intake manifold leak
- Inspect the exhaust system for the following:
- Water intrusion
- Exhaust leak
- Damaged, restricted, modified or enhanced exhaust system-Refer to Symptoms - Engine Exhaust .
- Inspect the engine mechanical for items that could alter the air flow into the combustion chamber. Refer to Symptoms - Engine Mechanical .