Part 1

2AZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P1422,P1423: Fuel Tank Small Leak

DTC P1422 - Fuel Tank Small Leak

DTC P1423 - Fuel Tank Gross Leak

DTC SUMMARY





DESCRIPTION

While the engine is running, if a predetermined conditions (closed loop, etc.) are met, the purge VSV is opened by the ECM (included in the 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 to enter 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.

























MONITOR DESCRIPTION

1. P1422: Fuel tank very small leak
In operation G, the vacuum pump creates negative pressure (vacuum) in the fuel tank and the fuel tank pressure is measured. If the stabilized system pressure is higher than the third 0.02 inch leak pressure standard, the ECM (included in the hybrid vehicle control ECU) determines that the fuel tank has a large leakage. The ECM illuminates the MIL and sets the DTC (2-trip detection logic).
2. P1423: Fuel tank gross leak
In operation G, the vacuum pump creates negative pressure (vacuum) in the fuel tank and the fuel tank pressure is measured. If the stabilized system pressure is higher than [third 0.02 inch leak pressure standard x 0.2] (near atmospheric pressure), the ECM (included in the hybrid vehicle control ECU) determines that the fuel tank has a large leakage. The ECM illuminates the MIL and sets the DTC (2-trip detection logic).





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS





Example of restart time:





Key-off monitor sequence 1 to 15

1. Atmospheric pressure measurement





2. First reference pressure measurement





3. Vent valve stuck closed check





4. Vacuum introduction for canister





5. Purge VSV stuck closed check





6. Second reference pressure measurement





7. Canister leak





8. Fuel vapor-containment valve (FVCV stuck closed check)





9. Vacuum introduction for fuel tank





10. FVCV stuck closed check





11. FTP sensor stuck check





12. Third reference pressure measurement





13. Fuel tank leak check





14. FTP sensor stuck check





15. Atmospheric pressure measurement





TYPICAL MALFUNCTION THRESHOLDS

"Saturated" indicates that the fuel tank pressure change is less than 0.1 kPa (0.75 mmHg) in 30 seconds.

P1423: Fuel tank gross leak





P1422: Fuel tank small leak





MONITOR RESULT

Refer to EVAP System .