Toyota Sienna check engine light issue related to EVAP system on Toyota Sienna

Some Toyota Sienna owners report experiencing issues with the check engine light related to the EVAP system, indicating problems with the vehicle's emissions control system. This may be triggered by an EVAP system fault, such as the OBD code P0440, which signifies an EVAP system leak. Common symptoms include the illumination of the check engine light, engine performance problems, and detection of emissions system faults. Diagnosing the issue typically involves inspecting components like hoses, gas caps, solenoids, valves, and the carbon canister. Repair costs can vary, with estimates around $375 for parts and $50 for labor. Owners often find that a loose or damaged gas cap can disrupt the fuel system, leading to the check engine light activation. Troubleshooting may require using a hand vacuum pump with a vacuum gauge to identify leaks, and various OBD codes such as P0441, P0442, and others indicate specific faults within the EVAP system. It is recommended not to conduct an EVAP system check when the fuel tank is over 90% full to ensure accurate results. Promptly addressing these issues is crucial to prevent further complications and potentially costly repairs in the future.