P0441

CIRCUIT DESCRIPTION

This diagnostic test is used to determine if the Evaporative Emission (EVAP) purge control solenoid is open when the PCM is commanding it open (energized). The PCM does this by monitoring the Evaporative Emission (EVAP) purge vacuum switch which is a normally closed switch mounted in the vacuum line between the EVAP canister and the EVAP purge solenoid. The switch opens when vacuum from the engine draws the evaporative emissions from the EVAP canister through the EVAP purge solenoid and into the throttle body. The PCM monitors the state of the EVAP purge vacuum switch to determine if the EVAP purge solenoid is open and passing vacuum. The PCM accomplishes this by monitoring the amount of time the EVAP purge vacuum switch is continuously open or closed during purge. When the test conditions are met the PCM starts a timer, which will be reset when the switch transitions open to closed or vice versa. If the switch remains closed for 9 seconds continuously, DTC P0441 is set. If the switch remains open for 2 seconds continuously, the test is passed.

CONDITIONS FOR SETTING THE DTC

Test Conditions

^ DTCs P0101, P0102, P0103, P0107, P0108, P0122, P0123, P0401, P0506, P0507, P1441, P1508, P1509 and P1645 not set.
^ IAT at key ON is greater than -25°C (-13°F).
^ IAT remains below 99.5°C.
^ ECT at key ON is at least 30°C less than previous key OFF ECT reading.
^ ECT is less than 125°C (257°F).
^ MAP is between 29.9 and 60 kPa.
^ Throttle position between 0 and 81.6 degrees.
^ Engine speed between 500 and 6375 RPM.
^ EVAP purge solenoid duty cycle at least 60%.
^ Barometric pressure (BARO) at least 72.
^ Engine vacuum at least 12 kPa.

Failure Condition

EVAP purge vacuum switch closed for 9 seconds and the EVAP purge vacuum switch has not been open for 2 seconds at any point during the test.

ACTION TAKEN WHEN THE DTC SETS

^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
^ A Last Test Failed DTC will clear when the diagnostic runs and does not fail.
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any diagnostic test.
^ PCM battery voltage is interrupted.
^ Using a Scan tool.

DIAGNOSTIC AIDS

Notice: Never apply voltage to the EVAP vacuum switch. The voltage supplied by the PCM is of a low current design. Switch damage could result if jumpered to voltage.

EVAP System Charcoal Contamination Checking Procedure

1. Remove EVAP Purge solenoid and the EVAP vacuum switch. Refer to R&R Procedures.
2. Lightly tap both components on a hard surface.
3. Check for the release of charcoal from either component.
4. If charcoal contamination is present replace the EVAP Vapor canister, EVAP Purge solenoid, EVAP Vacuum switch and clean the EVAP purge hoses. Refer to the EVAP Purge Hose Cleaning Procedure.

TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

3. Ensuring correct vacuum line connection and checking if fault conditions are present.
4. Checking if fault is vacuum or switch.
5. With a properly operating system the vacuum gauge can fluctuate rapidly while the solenoid is commanded On until 100% duty cycle is reached, at which point the vacuum should indicate the value specified. If the vacuum gauge indicates manifold vacuum immediately following 10% commanded On duty cycle then there is a restriction in the line or canister.