Circuit Description
WARNING: This page is about a different car, the 2003 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
- DTC P0441 -
The VSV for EVAP is used to purge the EVAP emissions from the fuel tank into the intake manifold. Together, VSV for CCV and VSV for EVAP are used to create a vacuum inside the fuel tank so that self monitoring leak tests are performed. When the VSV for EVAP remains open (opened malfunction), vacuum inside the fuel tank does not change, and consequently, when the VSV for EVAP remains open (opened malfunction), vacuum inside the fuel tank changes only when the VSV for CCV operates.
DTC will set when pressure in the EVAP emission control system does not drop during purge control function or when vacuum created in the EVAP emission control system does not stop when purge VSV for EVAP has cut-off command (two trip detection logic). See Fig 2 & Fig 3 .
- DTC P0446 - The VSV for CCV is open under normal conditions. When the VSV for EVAP is used to purge the EVAP emissions from the fuel tank into the intake manifold, air is drawn from the charcoal canister into the fuel tank. VSV for CCV has a function that relieves the pressure in case the pressure inside the fuel tank rapidly increases. Together, VSV for CCV and VSV for EVAP are used to create a vacuum inside the fuel tank so that self monitoring leak tests are performed. When the VSV for CCV remains closed (closed malfunction), the vacuum created inside the fuel tank cannot be relieved. When the VSV for CCV remains open (opened malfunction), vacuum in the fuel tank cannot be created. DTC will set when VSV for CCV is ON, pressure in EVAP emission control system is maintained at atmospheric pressure (2 trip detection logic). See Fig 2 & Fig 3 .
- DTC P0442 & P0456 -
The vapor pressure sensor, VSV for EVAP and VSV for CCV are used to detect abnormalities in the EVAP emission control system. The ECM determines whether abnormalities exist in the EVAP emission control system based on the signals from the vapor pressure sensor. If EVAP emissions leak from the components specified within the area between the dotted line in Fig 1, or if the vapor pressure sensor malfunctions, ECM records DTC P0442 or P0456. DTC will set when, after cold start, and after VSV for EVAP operation, the VSV for EVAP is turned off sealing the vacuum in the system and the ECM begins to monitor the pressure increase. ECM determines a very rapid, sharp increase in pressure indicates a leak in the EVAP system and sets DTC P0442. (Some increase is normal). This monitoring method is also able to distinguish what is called the small or very small leak detection (DTC P0456). A pressure rise just above normal indicates a very small hole (2 trip detection logic).
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002