P0442

DTC P0442 Evaporative Emission Control System Leak Detected (Small Leak)

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The vapor pressure sensor and VSV for vapor pressure sensor 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.

DTC P0440 is recorded by the ECM when evaporative emissions leak from the components within the dotted line in Fig. 1, or when the vapor pressure sensor malfunctions.

HINT: Typical DTC output of each trouble part

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions Part 1:

Typical Enabling Conditions Part 2:

Typical Malfunction Thresholds:

The evaporative emission system consists of the vapor pressure sensor, the CCV (Canister Close Valve), the pressure switching valve and the EVAP VSV (Purge VSV), those are used to detect malfunction in the system by ECM.

This test will run once per driving cycle when the ECM detects stable vapor pressure in the fuel tank. While the vehicle is being driven on rough or winding roads, the movement of the fuel in the tank will cause unstable fuel tank vapor pressure and the diagnostic test will not executed.

The ECM perform the following steps:
a. The CCV is closed. (shuts the system)
b. Checks the stability of the fuel tank pressure. If the variation in the pressure is greater than the specified value, disables the diagnosis.
c. Opens the EVAP VSV to introduce a negative pressure (vacuum) from the intake manifold into the fuel tank.
d. Closes the EVAP VSV to seal the fuel tank for storing the negative pressure.
e. Monitors the negative pressure in the fuel tank for:
1. Rapid decrease, i.e. a large leak, 0.040 inch or more
2. Decrease greater than the normal value

If the ECM detects either of above conditions, the ECM interprets this as a leak in the EVAP system. The ECM will illuminate the MIL (2-trip detection logic) and set a DTC.

MONITOR RESULT (MODE 06 DATA)

Monitor Result (Mode 06 Data):

Refer to "Monitors, Trips and/or Drive Cycle" for detailed information.

The test value and test limit information are described as shown in the table. Check the monitor result and test values after performing the monitor drive pattern.
- TID (Test Identification Data) is assigned to each emissions-related component.
- TID (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 Data) is assigned to each test value.
- Unit Conversion is used to calculate the test value indicated on generic OBD II scan tools.