Circuit Description
WARNING: This page is about a different car, the 2004 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
The vapor pressure sensor and the VSV for the canister closed valve (CCV) are used to detect abnormalities in the evaporative emission control system. The ECM decides whether there is an abnormality in the evaporative emission control system based on the vapor pressure sensor signal.
DTC P0442 or P0456 is recorded by the ECM when evaporative emissions leak from the components within the dotted line in Fig 1 below, or when the vapor pressure sensor malfunctions.
DTC DETECTION CONDITION
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0442 | After negative pressure introduction is completed, if the pressure in the EVAP system sharply increases, (small leak) (2 trip detection logic) |
|
| P0456 | If the pressure in the EVAP system slightly increases while the ECM performs a leak check, (very small leak) (2 trip detection logic) |
HINT:
Typical DTC output of each trouble part.
TROUBLE PART REFERENCE
| Trouble part | Typical DTC output ((1)) | |||||
| Small Leak | P0442 and/or P0456 ((2)) | |||||
| Medium Leak (ex: Vacuum hose loose) | P0442 | |||||
| Large Leak (ex: Fuel tank cap loose) | P0441 and P0442 and P0446 | |||||
| VSV for EVAP | Open Malfunction | P0441 | ||||
| Close Malfunction | P0441 and P0442 and P0446 | |||||
| VSV for CCV | Open Malfunction | P0441 and P0442 and P0446 | ||||
| Close Malfunction | P0446 | |||||
| VSV for Pressure Switching | Open Malfunction | P0446 | ||||
| Close Malfunction | P0441 and P0442 and P0446 | |||||
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