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)
–
DIAGNOSTICS
ENGINE (5VZ–FE)
DI–361
623
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
DTC
P0442
Evaporative Emission Control System Leak
Detected (Small Leak)
DTC
P0456
Evaporative Emission Control System Leak
Detected (Very Small Leak)
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.
DTC P0442 or P0456 is recorded by the ECM when evaporative emissions leak from the components within
the dotted line in Fig. 1 below, or when the vapor pressure sensor malfunctions.
DIA29–03
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
DI–362
–
DIAGNOSTICS
ENGINE (5VZ–FE)
624
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
After purge operation, the VSV for EVAP is turned off sealing the vacuum in the system and the ECM begins
to monitor the pressure increase. It is a normal if the increase in pressure is lower than the predict level. A
very rapid, sharp increase in pressure indicates a leak in the EVAP system and sets the DTC P0442.
A pressure rise just above normal indicates a very small hole and will set the DTC P0456.
DTC No.
DTC Detecting Condition
Trouble Area
P0442
P0456
After cold engine start.
After VSV for EVAP operation, the VSV for EVAP is turned off
sealing the vacuum in the system and the ECM begins to mon-
itor the pressure increase.
Some increase is normal.