Part 1

2AZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2450,P2451: Fuel Vapor-containment Valve Stuck Open

DTC P2450 - Fuel Vapor-containment Valve Stuck Open

DTC P2451 - Fuel Vapor-containment Valve Stuck Close

DTC SUMMARY

DESCRIPTION

While the engine is running, if a predetermined condition (closed loop, etc.) is met, the purge VSV is opened by the ECM (included in hybrid vehicle control ECU) and stored fuel vapors in the canister are purged to the intake manifold. The ECM will change the duty cycle ratio of the purge VSV to control purge flow volume.
Purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed into the canister through the vent valve to ensure that purge flow is maintained when negative pressure (vacuum) is applied to the canister.
The ECM monitors the condition of both the key-off monitor and purge flow monitor to ensure proper operation of the EVAP system.

Key-off monitor

This monitoring system checks for canister pump module malfunctions and leaks from the EVAP and closed tank systems. Be sure to leave the vehicle for at least 5 hours to sufficiently cool the fuel and stabilize fuel tank pressure. This makes EVAP system monitoring more accurate.

HINT: If the engine coolant temperature is 35°C (95°F) or more, 5 hours after the power switch has been turned off, the ECM will begin performing a monitor check after another 2 hours. If the engine coolant temperature is still 35°C (95°F) or more, 7 hours after the power switch has been turned off, the ECM will begin performing a monitor check after another 2.5 hours.

There are two methods for monitoring the EVAP system.
1. If the fuel tank pressure is higher or lower than the atmospheric pressure, the system determines that there are no leaks in the closed tank system and the system will check for leaks from the piping and canister between the purge VSV and canister pump module. (Method A)
2. If the fuel tank pressure is almost the same as the atmospheric pressure, vacuum pressure will enter the fuel tank and the system will check for leaks from the fuel tank after checking for leaks from the canister. (Method B)

HINT: *: If there is only a small amount of fuel in the fuel tank, stabilizing the EVAP pressure takes longer than usual.

Purge flow monitor

If EVAP system pressure change is less than 7.5 mmHg (1 kPa) when the engine is running and the purge VSV is turned ON (closed), the ECM determines that the purge flow is insufficient.

RELATED DTCS

MONITOR DESCRIPTION

1. P2450: Fuel vapor-containment valve (FVCV) stuck open
During sequence C, the vacuum pump creates vacuum pressure in the EVAP system. If the pressure in the fuel tank drops, the ECM (included in hybrid vehicle control ECU) determines that the fuel vapor-containment valve is stuck open. The ECM then illuminates the MIL and sets the DTC. (This DTC is set according to 2-trip detection logic.)
2. P2451: Fuel vapor-containment valve (FVCV) stuck closed (vent)
During sequence G, the fuel vapor-containment valve opens to allow vacuum pressure generated by the vacuum pump into the fuel tank. If the pressure in the fuel tank does not drop, the ECM determines that the fuel vapor-containment valve is stuck closed. The ECM then illuminates the MIL and sets the DTC. (This DTC is set according to 2-trip detection logic.)
During sequence I, the fuel vapor-containment valve opens to allow atmospheric pressure into the fuel tank. If there is no change in fuel tank pressure, the ECM determines that the fuel vapor-containment valve is stuck closed. The ECM then illuminates the MIL and sets the DTC. (This DTC is set according to 2-trip detection logic.)