A10142
ECM
Fuel Tank
Charcoal Canister
VSV for
EVAP
(1)
Fig. 1
(2)
(3)
(4)
(5)
(6)
(7)
Fuel Tank Over
Fill Check Valve
(10)
(9)
Vapor Pressure
Sensor
VSV for
CCV
VSV for
Pressure
Switching Valve
(8)
(11)
DI–328
–
DIAGNOSTICS
ENGINE (5VZ–FE)
590
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
DTC
P0441
Evaporative Emission Control System Incor-
rect Purge Flow
DTC
P0446
Evaporative Emission Control System Vent
Control Circuit
CIRCUIT DESCRIPTION
The vapor pressure sensor, VSV for EVAP, VSV for canister closed valve (CCV) and VSV for pressure
switching valve are used to detect abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTCs P0441 and P0446 are recorded by the ECM when there is a malfunction in either the VSV for EVAP,
the VSV for pressure switching valve, or in the vapor pressure sensor itself, or when evaporative emissions
leak from the components within the dotted line in Fig. 1 below.
DIA28–02
A20026
VSV for CCV
VSV for
Pressure Switching Valve
VSV for EVAP
Cold Start
ECT/IAT near same temp.
Negative
Pressure
Introduction
Tank & Canister
Leak Check
VSV for Pressure
Switching Valve, CCV
Testing
Open
Closed
Open
Closed
Open
Closed
Closed
Closed
Open
P0441
P0442, P0456
P0446
Inner Pressure in the tank
–
DIAGNOSTICS
ENGINE (5VZ–FE)
DI–329
591
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
P0441
The ECM closes the CCV and opens the VSV for pressure switching valve causing vacuum to increase in
the entire EVAP system.
The ECM continues to operate the VSV for EVAP until the vacuum is increased to a specified point at which
time the ECM closes the VSV for EVAP.
If the vacuum did not increase, or if the vacuum increased beyond the specified limit, the ECM judges the
VSV for EVAP and related components to be faulty.
P0446
When the vapor pressure rises to a specified point, the ECM opens the VSV for CCV. Pressure will increase
rapidly because of the air allowed into the sys