Circuit Description

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

The vapor pressure sensor and the vacuum switching valve (VSV) for the canister closed valve (CCV) are used to detect abnormalities in the evaporative emission control system. The engine control module (ECM) decides whether there is an abnormality in the evaporative emission control system, based on the vapor pressure sensor signal. DTCs P0451, P0452 or P0453 is recorded by the ECM when the vapor pressure sensor malfunctions. See Figure.

DTC P0451 detecting condition is when vapor pressure sensor output changes extremely under the following conditions (2 trip detection logic):

Vehicle speed is 0 mph (0 km/h) and engine speed is idling.
Vapor pressure sensor value is more than opening pressure value of charcoal canister.

DTC P0452 detecting condition is when after 10 seconds or more after engine idling, vapor pressure sensor output remains less than specific value (2 trip detection logic).

DTC P0453 detecting condition is when after 10 seconds or less after engine starting, vapor pressure sensor output remains more than specific value (2 trip detection logic).