Toyota Celica 2005 Repair Manual page 403

DI−204
MONITOR DESCRIPTION
P0441
The ECM checks for a stuck closed malfunction in the EVAP VSV by commanding it to open with the CCV
closed. If a high negative pressure does not develop in the fuel tank, the ECM determines that the EVAP
VSV remains closed. The ECM turns on the MIL and a DTC is set.
The ECM checks for EVAP VSV "stuck open" fault by commanding both valves (EVAP VSV and CCV) to
close at a time when the fuel tank is at atmospheric pressure. If the fuel tank develops a high negative pres-
sure at this early stage of the test, the ECM determines that the EVAP VSV is stuck open.
The ECM will turn on the MIL and a DTC will be set.
P0446
If there is a malfunction detected in the evaporative emission (EVAP) VSV, the canister closed valve (CCV)
and the pressure switching valve, the ECM will illuminate the MIL and set a DTC.
This portion of the EVAP diagnosis checks the following EVAP system functions:
(a) CCV stuck closed.
The ECM checks for a CCV "stuck closed" malfunction by commanding the CCV to open after an EVAP
leak test. If the fuel tank pressure does not rise (no vacuum generated), the ECM determines that the
CCV is stuck closed. The ECM will turn on the MIL and a DTC will be set.
(b) Pressure switching valve stuck closed.
The ECM checks for a pressure switching valve "stuck closed" malfunction by commanding the pres-
sure switching valve to close after an EVAP leak test. If the fuel tank pressure does not change, the
ECM determines that the pressure switching valve is malfunctioning. The ECM will turn on the MIL and
a DTC will be set.
(c) EVAP VSV (Purge line to intake manifold) stuck closed.
The ECM checks for a stuck closed malfunction in the EVAP VSV by commanding it to open with the
CCV closed. If a high negative pressure does not develop in the fuel tank, the ECM determines that
the EVAP VSV remains closed. The ECM will turn on the MIL and a DTC will be set.
MONITOR STRATEGY
Related DTCs
Required sensors/components
Frequency of operation
Duration
MIL operation
Sequence of operation
2005 CELICA (RM1131U)
DIAGNOSTICS −
P0441
P0446
Main sensors/components
Related sensors/components
Once per driving cycle
P0441 : 90 sec.
P0446 : 10 sec.
2 drive cycles
None
402
ENGINE (1ZZ−FE)
EVAP VSV malfunction
Canister close valve stuck closed
Pressure switching valve malfunction
EVAP VSV malfunction
Vapor pressure sensor
Engine coolant temperature sensor, Intake air
temperature sensor, Vehicle speed sensor