The P0302 diagnostic code on your 2021 GMC Yukon indicates that cylinder 2 is experiencing misfires detected by the engine control module. As a full-size SUV with V8 power, proper diagnosis maintains the Yukon's performance and reliability.
2021 Yukon Engine Configuration
The 2021 GMC Yukon features either the 5.3L V8 or the more powerful 6.2L V8 engine. Both engines include Dynamic Fuel Management (DFM), GM's advanced cylinder deactivation system that can shut down individual cylinders, including cylinder 2.
Dynamic Fuel Management Analysis
DFM allows the 5.3L and 6.2L V8s to operate on anywhere from 2 to 8 cylinders depending on power demand. Cylinder 2 can be deactivated during light-load driving. Problems with the DFM lifters or solenoids can cause misfires specifically related to cylinder deactivation events.
DFM Lifter Concerns
GM has acknowledged issues with DFM lifters in some applications. A collapsed or failing lifter can cause consistent misfires in the affected cylinder. Symptoms include valve train noise, rough running, and the P0302 code. Lifter replacement is the definitive repair.
Traditional Ignition Checks
Not all cylinder 2 misfires relate to DFM. Standard ignition system problems—worn spark plugs, failed coil packs, or wiring issues—remain common causes. The coil-on-plug design makes individual cylinder testing straightforward.
Fuel System Evaluation
Direct fuel injection problems can also cause cylinder-specific misfires. Test fuel pressure, inspect injector operation, and evaluate fuel quality. The high-pressure fuel system requires professional diagnostic equipment for complete testing.