P0441

DTC P0441 Evaporative Emission Control System Incorrect Purge Flow

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

Figure 1

MONITOR DESCRIPTION

P0441
The ECM closes the canister closed valve (CCV) and opens the VSV for pressure switching valve (bypass VSV) causing a vacuum to increase in the entire EVAP system.
The ECM continues to operate the EVAP VSV until the vacuum is increased to a specified point.
If the vacuum did not increase, or if the vacuum increased beyond the specified limit, the ECM judges the EVAP VSV and related components faulty.
P0446
When the vapor pressure rises to a specified point, the ECM opens the CCV. Pressure will increase rapidly because of the air is 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 bypass VSV. This action blocks air entering the fuel tank side of system.
If there was no change in the pressure, the ECM will conclude that the bypass VSV did not close.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS
Same as P0442 refer to P0442

TYPICAL MALFUNCTION THRESHOLDS

MONITOR RESULT

The detailed information is described in "CHECKING MONITOR STATUS" Checking Monitor Status
- TID (Test Identification) is assigned to each emission-related component.
- TLT (Test Limit Type):
If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
- CID (Component Identification) is assigned to each test value.
- Unit Conversion is used to calculate the test value indicated on generic OBD scan tools.

TID $02: EVAP - Vacuum Monitor

WIRING DIAGRAM

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- If DTC P0441 (Purge Flow), P0446 (VSV for CCV or VSV for Pressure switching valve), P0450 or P0451 (Evaporative Pressure Sensor) is output together with DTC P0442 or P0456, first troubleshoot DTC P0441, P0446, P0450 or P0451. 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. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.

Hand-held tester: