P0441

EVAP CANISTER PURGE VALVE, LOW FLOW





Symptom Of Fault.
CHECK ENGINE lamp (MIL) on.
Any other diagnostic trouble codes (closed loop, misfiring)

Conditions.
^ Diagnosis not yet performed this drive cycle.
^ Front heated oxygen sensor OK.
^ Vehicle speed = 0.
^ Idling speed.
^ Closed loop active.
^ Coolant temperature > 60°C (> 140°F)
^ No load changes
^ Steady idling speed
Additional fuel from purging < 10% of engine fuel needs and no change in closed loop or idle speed control when purging activated.

Diagnostic Help.
The diagnostic trouble code indicates that the flow through the purge valve is too low.
Whether air or fuel vapor is sucked through the valve is of no importance.
Since a fault in the purge valve's electrical circuit is indicated by a different diagnostic trouble code, fault diagnosis concerns a mechanical fault.
It is important to ensure that no hoses are pinched or kinked.





Diagnostic Procedure.
1. Check the valve
- Ignition switch in the OFF position.
- Disconnect the purge valve hose from the intake manifold.
- Connect the pressure/vacuum pump and create a vacuum. The pressure must not rise.

Does the pressure rise?
YES:
^ Repair or replace the hose connected to the valve or the valve itself. Continue with point 3.
NO:
^ Ignition switch in the OFF position. Continue with point 2.





2. Check the air flow
- 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.
- Connect the pressure/vacuum pump to the hose again and create a vacuum.

A steady flow should now be obtained from the evaporative emission canister via the valve (the sound of the valve pulsating can also be heard in the hose).

Is a steady flow obtained?
YES:
^ Reconnect the hose and continue with point 3.
NO:
^ Repair or replace the hose. Change the valve or evaporative emission canister if necessary, and continue with point 3.

NOTE: The purge valve is active for 4 1/2 minutes and then idle for 1/2 minute, and so on.





3. 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 EDU 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 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 WOW.
- Select "DIAGNOSTIC STATUS".
- Select "EVAP"

Does the ISAT scan tool show "NOT READY"?
YES
^ Repeat the driving cycle.
^ Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?
YES
^ Proceed at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO:
^ The remedial measure taken was correct.
- Plug the temperature sensor into the EDU.
- Clear the diagnostic trouble code for the temperature sensor in the EDU.