The 2020 Chevrolet Suburban offers the 5.3L V8 (355 hp) or 6.2L V8 (420 hp), both featuring Active Fuel Management (AFM) cylinder deactivation. When P0306: Cylinder 6 Misfire Detected triggers your check engine light, your Suburban has identified combustion problems in cylinder 6.
Final K2XX Platform Year
The 2020 Suburban represents the last year of the previous generation before the T1 platform redesign. The V8 engines use AFM to improve fuel economy by deactivating cylinders—including cylinder 6—under light loads. This system requires properly functioning lifters and valve train components.
Common P0306 Causes
AFM lifter wear affects valve operation on specific cylinders. Ignition coil degradation reduces spark quality. Spark plugs approaching service intervals produce weak combustion. Direct injection allows carbon buildup. Fuel injector issues affect fuel delivery.
Diagnostic Approach
Scan for all codes including AFM-related faults. Listen for lifter tick indicating potential valve train issues. Access cylinder 6 and inspect ignition components. Remove and evaluate spark plug condition. Test fuel injector operation. Perform compression testing to assess mechanical health.
Full-Size SUV Reliability
The Suburban's family-hauling and towing capability demands reliable V8 performance. Quality diagnosis and repair ensures continued service for demanding duty.