Fig. 181: Evaporative Emission Control System Operation Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
a. P0455: EVAP gross leak
In operation C, the leak detection 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 reference
pressure x 0.2] (near atmospheric pressure), the ECM determines that the EVAP system has a large
leakage, illuminates the MIL and stores the DTC (2 trip detection logic).
b. P0456: EVAP very small leak
In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the
EVAP system pressure is measured. If the stabilized system pressure is higher than the second reference
pressure, the ECM determines that the EVAP system has a small leakage, illuminates the MIL and stores
the DTC (2 trip detection logic).
B
pressure
measurement
and then ECM checks if leak detection pump and vent valve
operate normally.
seconds
C
EVAP system
pressure
measurement
Vent valve turned ON (closed) to shut EVAP system.
Negative pressure (vacuum) created in EVAP system, and
EVAP system pressure then measured.
Write down measured value as it will be used in leak check.
If EVAP pressure does not stabilize within 15 minutes, ECM
cancels EVAP system monitor.
15
minutes
(1)
D
Purge VSV monitor
Purge VSV opened and then EVAP system pressure measured
by ECM.
Large increase indicates normality.
10
seconds
E
Second reference
pressure
measurement
After second reference pressure measurement, leak check
performed by comparing first and second reference pressure.
If stabilized system pressure higher than second reference
pressure, ECM determines that EVAP system leaking.
60
seconds
-
Final check
Atmospheric pressure measured and then monitoring result
recorded by ECM.
-
(1)
If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.
2009 Toyota Tundra
2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra