P0446

DTC P0446 Evaporative Emission Control System Vent Malfunction

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CIRCUIT DESCRIPTION
The vapor pressure sensor and VSV for vapor pressure sensor 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 P0441 and P0446 are recorded by the ECM when evaporative emissions leak from the components within the dotted line in fig. 1 above, or when there is a malfunction in either the VSV for EVAP, the VSV for vapor pressure sensor, or in the vapor pressure sensor itself.

DETECTING CONDITIONS

WIRING DIAGRAM

INSPECTION PROCEDURE

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TOYOTA hand-held tester:

HINT
- If DTC P0441 (Evaporative Emission Control System Incorrect Purge Flow), P0446 (Evaporative Emission Control System Vent Control Malfunction), P0450 (Evaporative Emission Control System Pressure Sensor Malfunction) or P0451 is output after DTC P0440 (Evaporative Emission Control System Malfunction), first troubleshoot DTC P0441, P0446, P0450 or P0451. If no malfunction is detected, troubleshoot DTC P0440 next.
- Read freeze frame data using TOYOTA hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining whether the vehicle was running or stopped, the engine warmed up or not, the air-fuel ratio lean or rich, etc. at the time of the malfunction.
- When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the VSV for EVAP, charcoal canister and vapor pressure sensor.