EVAP SYSTEM OPERATION INFORMATION ± EG005-01 April 27, 2001
Page 4 of 14
Vapor Purge Flow P0441
The EVAP monitor is designed to detect:
Restricted vapor purge flow when the
purge VSV is open
Inappropriate vapor purge flow when
the purge VSV is closed
Under normal purge conditions, pressure
pulsations generated by the cycling of the
purge VSV are present in the canister
and detected by the Vapor Pressure
sensor.
Three±Way VSV P0446
The three±way VSV is connected to the Vapor Pressure sensor, canister, and fuel tank.
This VSV allows the Vapor Pressure sensor to detect either canister or tank pressure.
There are two modes the ECM can use to determine if the three±way VSV is
malfunctioning. The three±way VSV is judged to be normal if there is pressure difference
between the tank and canister when the three±way VSV is switched to look at the
charcoal canister and fuel tank side of system.
If there isn't any pressure difference between the fuel tank and canister, the ECM looks
for the following conditions:
During purging, pressure pulsations generated by the purge VSV are not present in
the canister as detected by Vapor Pressure sensor, the three±way VSV is judged to
be defective.
If there are pressure pulsations detected by the Vapor Pressure sensor present in the
fuel tank, the three±way VSV is judged to be defective.
Late Type (Intrusive) EVAP System Overview
The Late Type EVAP System, also known as the Intrusive type, was developed to meet
the very stringent, mandated standard of detecting a hole 0.020 inch (0.5 mm). This
system uses many of the same components as the early type EVAP system. Purge,
vacuum relief, pressure relief, and ORVR operations are identical to the early type. Refer
to the Applicable Vehicles chart for applicability information.
The following changes were made to the Late Type EVAP System:
Vapor pressure sensor connected to the fuel tank.
Bypass VSV in the place of the three way VSV.
Canister Closed Valve (CCV) on the air inlet line.Early Type
System
Description
(Continued)
Figure 5. Flow During Purge Operation
Late Type
System
Description
Toyota Supports ASE CertificationPage 1 of 5
EG013-02Title:
M.I.L. ON" P0440, P0441 & P0446
Models:
'98 ± '99 Camry & Solara
Technical Service
BULLETIN
July 12, 2002
Under certain driving conditions, some 1998 ± 1999 model year Camry and Solara
vehicles may exhibit a M.I.L. ªONº with DTCs P0440, P0441 and P0446 stored due to an
inoperative Vapor Pressure Sensor 3 way Vacuum Switching Valve (VSV). An improved
Vapor Pressure Sensor VSV has been developed to correct this condition.
1998 ± 1999 model year Camry & Solara vehicles.
PREVIOUS PART NUMBERCURRENT PART NUMBERPART NAMEQTY
90910±1210990910±12271Vapor Pressure Sensor VSV1
TOOLS & MATERIALPART NUMBERQUANTITY
Toyota Diagnostic Tester Kit*
010012711
12 Megabyte Diagnostic Tester Program Card
with version 9.01a Software (or later)*
01002593-0051
Hand Operated Vacuum PumpN/A1
Digital Volt Ohm Meter (DVOM)09082±00050
(Or Equivalent)1
* Essential SSTs.
NOTE:
Additional Diagnostic Tester Kits, Program Cards or SSTs may be ordered by calling
OTC at 1-800-933-8335.
OP CODEDESCRIPTIONTIMEOFPT1T2
178011
R & R Vacuum Switching Valve (4 Cylinder)0.4
90910 121097283178011R & R Vacuum Switching Valve (6 Cylinder)0.290910±121097283
Applicable Warranty*:
This repair is covered under the Toyota Comprehensive Warranty. This warranty is in
effect for 36 months or 36,000 miles, whichever occurs first, from the vehicle's
in-service date.
* Warranty application is limited to correction of a problem based upon a customer's specific complaint.
ENGINE
Introduction
Applicable
Vehicles
Parts
Information
Required Tools
& Material
Warranty
Information
