Diagnostic Aids

WARNING: This page is about a different car, the 2003 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

If DTC P0441 (purge flow), P0446 (VSV for CCV or VSV for pressure switching valve), P0451, P0452 or P0453 (evaporative pressure sensor) is output with DTC P0442 or P0456, first troubleshoot DTC P0441, P0446, P0451, P0452 or P0453. If no malfunction is detected, troubleshoot DTC P0442 or P0456 next.

Check if owner found fuel tank cap was loose and tightened it. Check if fuel tank cap was loose when refuelling. If cap was loose, it was the cause of the DTC. If fuel tank cap was not loose or if owner was not sure if it was loose, troubleshoot according to the following procedure.

Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich at the time of the malfunction. When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.