The P0302 code on your 2023 Toyota Sienna signals cylinder 2 misfire detected by the powertrain control module. The Sienna's 2.5L hybrid powertrain continues from 2021, but as a newer model, warranty coverage is likely available.
2023 Sienna Powertrain
The 2023 Sienna uses the 2.5L A25A-FXS hybrid powertrain with either front-wheel drive or all-wheel drive configurations. The engine operates with hybrid motor assistance, cycling on and off based on driving demands.
Warranty Status
Your 2023 Sienna should be under Toyota's warranty—3-year/36,000-mile basic and 5-year/60,000-mile powertrain coverage. Engine misfire issues qualify for warranty repair at no cost.
Potential Causes
On a relatively new vehicle, cylinder 2 misfire may result from manufacturing defect in ignition coil, spark plug installation issue, fuel injector problem, or rarely, software calibration needing update.
Recommended Action
For a warranty-covered vehicle, Toyota dealer diagnosis is recommended. They document the repair properly and have access to TSBs and latest repair information for the current model.