The 2021 GMC Yukon full-size SUV offers the 5.3-liter V8 and 6.2-liter V8 engines, both featuring Dynamic Fuel Management (DFM) cylinder deactivation technology. A P0305 diagnostic trouble code indicates the engine management system has detected a misfire at cylinder 5, which is a legitimate position on these V8 engines.
Understanding P0305 on Yukon V8
The P0305 code signifies "Cylinder 5 Misfire Detected." On GM V8 engines, cylinder 5 is on the driver's side (left bank). The DFM system can deactivate cylinder 5 among other cylinders during light-load operation for improved fuel economy.
DFM System Considerations
Dynamic Fuel Management represents GM's latest cylinder deactivation technology, capable of seamlessly deactivating any combination of cylinders. The switching lifters required for DFM operation can develop issues causing misfires, particularly at cylinder 5 if its lifter fails.
Standard Misfire Causes
Beyond DFM concerns, traditional misfire causes apply: worn spark plugs approaching the 100,000-mile interval, failing ignition coils, fuel injector problems, intake manifold gasket leaks, or carbon buildup on direct injection engines affecting intake valve airflow.
Diagnostic Priority
Given DFM complexity, diagnosis should evaluate both traditional misfire causes and DFM lifter function. Listen for lifter tick and monitor misfire patterns during DFM cycling versus steady-state operation.