Possible Causes

DTC detection conditions are:

• For DTC P0451: Vapor pressure sensor output extremely changes under conditions when vehicle speed is zero MPH and engine speed is idling. Vapor pressure sensor value is greater than or equal to opening pressure value of charcoal canister, (2 trip detection logic).
• For DTC P0452: 10 seconds or more after engine starting condition vapor pressure sensor fixed value continues to be a fixed value or less, (2 trip detection logic).
• For DTC P0453: 10 seconds or less after engine starting condition vapor pressure sensor fixed value continues to be a fixed value or more, (2 trip detection logic).

• Vapor pressure sensor circuit is open or shorted.
• Defective vapor pressure sensor.
• Defective ECM.