P0442

LEAKAGE IN THE PURGING SYSTEM





Symptom Of Fault.
The CHECK ENGINE lamp (MIL) is on. Possible fuel odor.

Conditions.
^ Diagnosis not yet performed this trip
^ Front heated oxygen sensor OK.
^ Vehicle speed = 0 for 7 sec.
^ Idling speed
^ Purge valve active
^ Additional fuel from purging < 10 of engine's fuel requirement.

P0455: Serious leakage.
When the supply air for the evaporative emission canister is shut off and purging is active, no pressure drop occurs in the tank.

P0442: Little leakage.
When the supply air for the evaporative emission canister is shut off and purging is active, pressure drops in the tank.
When purging is subsequently stopped, however, the pressure rises too fast.





Diagnostic Help.
The diagnostic trouble code indicates a leak in one of the following components:

^ Fuel filler cap not tightened properly, damaged seal, etc.
^ Filter pipe or breather pipe.
^ Tank, above surface of fuel
^ Line from rollover valve to evaporative emission canister.
^ Evaporative emission canister.
^ Evaporative emission canister shut-of valve.
^ Line from evaporative emission canister to canister purge valve.
^ EVAP canister purge valve.

The evaporative emission canister's shut-of valve can be activated by the ISAT scan tool.

- Select "ACTIVATE".
- Select "CANIST.CLOSE VALVE"

A tank pressure reading can be obtained with the ISAT scan tool.

- Select"READ FUNCTIONS".
- Select "TANK PRESSURE"

A diagnostic trouble code will also be generated in the event of a break in the circuit for the evaporative emission canister's shut-of valve and an incorrect constant reading from the tank pressure sensor.

Checking The Wiring
Intermittent faults may occur as a result of occasional short circuits and breaks in the wiring. Jiggle the leads and in-line connectors at several places and in different directions to reveal faults in the wiring harness. Observe the multimeter, ISAT scan tool or test lamp while carrying out this check.





Diagnostic Procedure.
1. Check the fuel filler cap

- if possible, check whether the filler cap was properly tightened when the fault was discovered.
- Check whether the filler cap is properly tightened.
- Check the filler cap's seal and sealing surfaces.

Is the fuel filler cap OK?
YES: Continue with point 2.
NO: Rectify the fault and proceed to point 5.

2. Check the fuel leakage

- Fill the tank with fuel right up to the top of the filler pipe.
- Check visually whether any fuel leaks out from the tank, filler pipe or breather pipe.

Any leakage?
YES: Rectify the fault and proceed to point 5.
NO: Continue with point 3.





3. Check the purge valve

- Check that the purge valve is closed when no current is applied to it and opens when current is applied.

All OK?
YES: Continue with point 4.
NO: Change the valve and proceed to point 5.





4. Check the purging circuit

- Ignition switch in the OFF position.
- Unplug the connector from the evaporative emission canister's shut-of valve.
- Connect the shut-of valve (male connector) to the battery.
- Connect a pressure/vacuum pump and pressure gauge to the evaporative emission canister's hose.
- Remove the filler cap and close off the rollover valve hole.
- Using the pressure/vacuum pump, lower the pressure to -0.1 bar.

The pressure should not visibly rise for 10 seconds.

Does the pressure rise?
YES: The leakage has been traced to the evaporative emission canister, including the lines connected to it, or the shut-of valve. To check the electrical operation of the shut-of valve, use the ISAT scan tool and activate the appropriate function.
Rectify the fault and proceed to point 5.
NO: Change the filler cap and continue with point 5.





5. Final check:

- Clear the diagnostic trouble code.
- Perform a driving cycle:

^ Ignition switch in the ON position, A/C switched off and temperature sensor unplugged from the Integrated Central Electronics (ICE) so that the radiator fan runs continuously.
^ Start the engine and run it at idling speed until the temperature of the coolant exceeds 60°C (140°F) or for at least 1 minute if this temperature is reached earlier.
^ Depress the accelerator for a second or two and then run the engine at idling speed for 30 seconds. Repeat three times.

- Evaluation of the driving cycle:
- Connect an ISAT scan tool.
- Select "READ ON/OFF".
- Select "DIAGNOSTIC STATUS".
- Select "EVAP"

Does the ISAT scan tool show "NOT READY"?
YES: Repeat the driving cycle.
NO: Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?
YES: Continue at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO: The remedial measure taken was correct.

- Plug the temperature sensor into the ICE.
- Clear the diagnostic trouble code for the temperature sensor in the ICE.