P0446

DTC P0446 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL CIRCUIT

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The vapor pressure sensor, VSV for canister closed valve (CCV), 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 evaporative emissions leak from the components within the dotted line in Fig. 1, or when there is a malfunction in either the VSV for EVAP the VSV for pressure switching valve, or in the vapor pressure sensor itself.

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 system. No increase or an increase below specified rate of pressure increase indicates a restriction on the air inlet side.

The ECM closes the VSV for pressure switching valve. This action blocks air entering the fuel tank side of system. The pressure rise on the fuel tank side is no longer great.

If there was no change in pressure, the ECM will conclude the VSV for pressure switching valve did not close.






HINT: Typical DTC output of each trouble part

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- If DTC P0441 (Purge Flow), P0446 (VSV for CCV or VSV for Pressure switching valve) P0451, P0452 or P0453 (Evaporative Pressure Sensor) is output 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 the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
- When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.

Step 1 - 3:

Step 4 - 7:

Step 8 - 11:

Step 12 - 15:

Step 16 - 19:

Step 20 - 21:

Step 22 - 24:

Step 25 - 30:

Step 31 - 35:

Step 36 - 41:

Step 42 - 47:

Step 48 - 52:

Step 53 - 56:

Step 57 - 58:

Hand-held Tester

Step 1 - 4:

Step 5 - 8:

Step 9 - 11:

Step 12 - 13:

Step 14 - 16:

Step 17 - 19:

Step 20 - 23:

Step 24:

OBDII scan tool (excluding Hand-held Tester)