| CAUTION | If ECM replacement is instructed in following tests, always ensure ECM connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. |
Note. If DTCs P0441, P0446, P0450 or P0451 is output after DTC P0440, perform appropriate test first before performing DTC P0440 test.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Vapor pressure sensor and canister closed valve Vacuum Switching Valve (VSV) are used to detect faults in EVAP system. DTC is set if vapor pressure sensor malfunctions. Possible causes are
- Vapor pressure sensor circuit is open or shorted.
- Defective vapor pressure sensor.
- Defective ECM.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected. When ENGINE RUN TIME in freeze frame data is less than 200 seconds, check EVAP VSV, charcoal canister and vapor pressure sensor.