Circuit Description

Vapor pressure sensor, canister closed valve Vacuum Switching Valve (VSV) and pressure switching valve VSV are used to detect faults in EVAP system. DTC P0450 is set if 10 seconds after engine starts, vapor pressure sensor fixed value continues for a predetermined amount of time. DTC P0451 is set if vapor pressure sensor output changes while vehicle is standing at idle and pressure switching valve VSV is off. Possible causes are:

• Open or short in vapor pressor sensor circuit.
• Faulty vapor pressure sensor.
• Faulty ECM.