Toyota Sienna Service Manual: Evaporative Emission Control System Leak Detected

DTC P0455 Evaporative Emission Control System Leak Detected (Gross Leak)

DTC P0456 Evaporative Emission Control System Leak Detected (Very Small Leak)

DTC SUMMARY

DESCRIPTION

The circuit description can be found in the EVAP (Evaporative Emission) System.

INSPECTION PROCEDURE

Refer to the EVAP System.

MONITOR DESCRIPTION

5 hours*1 after the ignition switch is turned off, the electric vacuum pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT: *1: If the engine coolant temperature is not below 35C (95F) 5 hours after the ignition switch is turned off, the monitor check starts 2 hours later. If it is still not below 35C (95F) 7 hours after the ignition switch is turned off, the monitor check starts 2.5 hours later.

*2: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

1.  P0455: EVAP (Evaporative Emission) gross leak
   In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [second 0.02 inch leak pressure standard x 0.2] (near atmospheric pressure), the ECM determines that the EVAP system has a large leak, illuminates the MIL and sets the DTC (2 trip detection logic).
2. 2. P0456: EVAP very small leak
   In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than second 0.02 inch leak pressure standard, the ECM determines that the EVAP system has a small leak, illuminates the MIL and sets the DTC (2 trip detection logic).

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

Key-off monitor sequence 1 to 8

1. Atmospheric pressure measurement

2. First reference pressure measurement

3. EVAP canister vent valve close stuck check

4. Vacuum introduction

5. EVAP canister purge valve close stuck check

6. Second reference pressure measurement

7. Leak check

8. Atmospheric pressure measurement

TYPICAL MALFUNCTION THRESHOLDS

P0455: EVAP gross leak

P0456: EVAP 0.02 inch leak

MONITOR RESULT

Refer to CHECKING MONITOR STATUS