P0441

DTC P0441 EVAPORATIVE EMISSION CONTROL SYSTEM INCORRECT PURGE FLOW
DTC P0446 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL MALFUNCTION

CIRCUIT DESCRIPTION

DTC Detection Conditions:

The vapor pressure sensor, VSV for CCV (Vacuum Switching Valve for Canister Closed Valve), VSV for EVAP (Evaporative Emission), and VSV for pressure switching valve are used to detect abnormalities in the EVAP control system.

The ECM determines whether there is an abnormality in the EVAP control system based on the vapor pressure sensor signal.

DTCs P0441 and P0446 are set by the ECM when evaporative emissions leak from the components within the dotted line in Fig. 1 below, and when there is a malfunction in the VSV for CCV, VSV for EVAP, and VSV for pressure switching valve, or in the vapor pressure sensor itself.

HINT: Typical DTC outputs of each trouble area are as follows.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

The ECM checks the EVAP (Evaporative Emission) system using the vapor pressure sensor, CCV (Canister Closed Valve), VSV (Vacuum Switching Valve) for EVAP, and VSV for pressure switching valve. The ECM closes the EVAP system and introduces negative pressure (a vacuum) into it. The ECM then monitors the internal pressure using the vapor pressure sensor.

The VSV for EVAP is used to discharge the evaporative emissions from the fuel tank into the intake manifold via the canister. In addition, it creates negative pressure (a vacuum) inside the fuel tank simultaneously with the operation of the VSV for CCV to conduct leak tests.

P0441

DTC P0441 is set if either one of the following conditions applies:
- VSV for EVAP stuck closed malfunction:
The ECM checks for the malfunction by signaling the VSV for EVAP to open with the VSV for CCV (vent) closed. If a highly negative pressure does not develop in the fuel tank, the ECM determines that the VSV for EVAP remains closed and illuminates the MIL and sets the DTC.

- VSV for EVAP stuck open malfunction:
The ECM checks for the malfunction by signaling both the VSV for EVAP and VSV for CCV to close at a time when the internal fuel tank pressure level is equal to the atmospheric pressure. If a highly negative pressure develops in the fuel tank at this early stage of the check, the ECM determines that the VSV for EVAP is stuck open, and illuminates the MIL and sets the DTC.

P0446

The ECM illuminates the MIL and sets the DTC if any of the following malfunctions apply:
- CCV stuck open malfunction:
The ECM checks for the malfunction by signaling the VSV for EVAP to open with the CCV closed to create the negative pressure in the fuel tank. If the fuel tank does not develop an appropriate highly negative pressure, the ECM determines that the CCV is stuck open.

- CCV stuck closed malfunction:
The ECM checks for a stuck closed malfunction in the CCV by signaling it to open after an EVAP leak test. If the internal fuel tank pressure does not rise (the vacuum decreases), the ECM determines that the CCV is stuck closed.

- VSV for Pressure Switching Valve stuck closed malfunction:
The ECM checks for a stuck closed malfunction in the VSV for pressure switching valve by signaling it to close after an EVAP leak test. If the internal fuel tank pressure does not change, the ECM determines that the VSV for pressure switching valve is stuck closed.

MONITOR RESULT

Refer to Checking Monitor Status for detailed information. Mode 6 Data

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- If any of DTC P0441 (Purge Flow), P0446 (VSV for CCV or VSV for Pressure Switching Valve), P0451, P0452 or P0453 are set simultaneously with DTC P0442 or P0456 , first troubleshoot DTC P0441, P0446, P0451, P0452 or P0453. If no malfunction is detected, troubleshoot DTC P0442 or P0456 next.
- Read freeze frame data using a hand-held tester or OBD II scan tool. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
- When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.