The 2020 Toyota 4Runner features the proven 4.0L 1GR-FE V6 engine producing 270 horsepower, powering this capable off-road SUV. When P0306: Cylinder 6 Misfire Detected triggers your check engine light, your 4Runner's engine management has identified combustion problems in cylinder 6.
4Runner V6 Engine Configuration
Toyota's 4.0L V6 positions cylinder 6 on the rear bank of the longitudinally-mounted engine. Unlike many modern engines, the 1GR-FE uses port fuel injection with proven reliability and no direct injection carbon buildup concerns. The 4Runner's off-road capability means the engine may experience more dust exposure and varied operating conditions.
Common P0306 Causes
Ignition coil failure from heat cycling affects the coil-on-plug units, particularly on rear cylinders. Spark plug degradation over time reduces ignition efficiency. Fuel injector clogging from fuel quality or debris prevents proper atomization. Vacuum leaks around the intake manifold create lean conditions. Off-road use may accelerate air filter and fuel filter maintenance needs affecting combustion.
Diagnostic Procedure
Scan for all codes to identify if P0306 appears alone or with other issues. Access the rear cylinder bank—the 4Runner's longitudinal engine layout provides reasonable access. Inspect cylinder 6's coil-on-plug for damage and test functionality. Remove and examine the spark plug condition. Verify fuel injector operation. Perform compression testing to assess mechanical cylinder health.
Off-Road Vehicle Considerations
4Runner owners who venture off-road should maintain aggressive air filter replacement schedules. Ensure fuel system cleanliness with quality fuel and consider periodic injector cleaning to prevent deposits.