A P0303 code on your 2021 Toyota Sienna indicates that the engine control module has detected cylinder 3 misfires beyond acceptable parameters. The redesigned Sienna features a standard hybrid powertrain.
2021 Sienna: Hybrid-Only
The 2021 Toyota Sienna debuted as a hybrid-only model, using a 2.5L Dynamic Force four-cylinder engine with electric motors for 245 combined horsepower. No gas-only option is available.
Dynamic Force Engine
The 2.5L features D-4S dual injection combining direct and port injection. This technology helps prevent carbon buildup while optimizing efficiency for hybrid operation.
Four-Cylinder Configuration
Each cylinder produces 25% of combustion power. Cylinder 3 misfires affect engine operation, though electric assistance provides some compensation during driving.
Family Minivan Priority
The Sienna serves as primary family transportation for many owners. Reliable operation is essential for daily driving and road trips.
Hybrid System Benefits
The hybrid system provides excellent fuel economy for a minivan. Misfires reduce this efficiency. Address them to maintain optimal operation.