P0446
DTC P0446 Evaporative Emission Control System Vent Control CircuitDESCRIPTION
DTC Detection Condition:
This DTC is designed to detect the pressure switching valve (3-way VSV) malfunction. If the malfunction is detected while the vehicle is running, the ECM illuminates the MIL and sets a DTC (2 detection logic). The pressure switching valve located on the canister is used to detect leakage from the bladder tank into the fuel tank. The valve opens during the bladder tank leak check. Then, the fuel tank's fuel vapor flows to the intake manifold without passing the canister.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions (Part 1):
Typical Enabling Conditions (Part 2):
Typical Malfunction Thresholds:
Pressure switching valve is stuck OFF (Closed)
The pressure switching valve opens when the purge VSV opens while the vehicle is running. Then, the fuel tank pressure drops 2 mmHg or more when the pressure switching valve is normal. If the pressure does not change, the ECM interprets this as a malfunction. The ECM illuminates the MIL and sets a DTC (2 trip detection logic).
Pressure switching valve is stuck ON (Open)
In order to depressurize the fuel tank, the pump module's vent valve is turned ON (close) when the purge VSV opens while the vehicle is running. After the fuel tank pressure drops 20 mmHg, the purge VSV closes. Then, the fuel tank pressure rises slightly when the pressure switching valve is normal. If the pressure rises quickly, the ECM interprets this as a malfunction. The ECM illuminates the MIL and sets a DTC (2 trip detection logic).
Wiring Diagram:
Wiring Diagram:
INSPECTION PROCEDURE
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