PZEV Engine

DTC P0441 EVAPORATIVE EMISSION CONTROL SYSTEM INCORRECT PURGE FLOW

MONITOR DESCRIPTION

DTC Detection Condition:

Monitor Strategy:

Typical Enabling Conditions:

Typical Enabling Conditions Part 1:

Typical Enabling Conditions Part 2:

Typical Enabling Conditions Part 1:

Typical Enabling Conditions Part 2:

Typical Malfunction Thresholds:

Monitor Result (Mode 06 Data):

The ECM tests the evaporative emissions (EVAP) system using the fuel tank pressure sensor, the canister close valve (CCV), and the EVAP VSV. The ECM closes the EVAP system and introduces a negative pressure (vacuum) into it. The ECM then monitors the internal pressure using the fuel tank pressure sensor. (Refer to graphic).

P0441

The EVAP VSV is used to purge the evaporative emissions from the fuel tank into the intake manifold. Also, it creates a negative pressure (vacuum) inside the fuel tank in unison with the operation of the CCV (canister closed valve) and leak tests are performed using this vacuum.

Opening or closing malfunctions in the EVAP VSV prompt the ECM to set DTC P0441.

The ECM checks for a EVAP VSV "stuck closed" fault by commanding the EVAP VSV open with the CCV (vent) closed. The fuel tank should develop a high negative pressure (vacuum). If it does not, the ECM determines that the despite an OPEN command, the EVAP VSV remained closed. The ECM turns on the MIL and a DTC is set.

The ECM checks for a EVAP VSV "stuck open" fault by commanding both valves (EVAP VSV and CCV) closed at a time when the fuel tank is at atmospheric pressure. If the fuel tank develops a high negative pressure (vacuum) at this early stage of the test, the ECM determines that the EVAP VSV is stuck OPEN. The ECM will turn on the MIL and DTC is set.

EVAP LEAK TEST

a. Connect the hand-held tester to the DLC3.
b. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / EVAP SYS CHECK (or EVAP LEAK TEST) mode on the hand-held tester.

c. If any changes do not occur within 1 minute after pressing "EVAP LEAK TEST", remove the fuel tank cap, then set the fuel tank cap again. Perform "EVAP SYS CHECK (or EVAP LEAK TEST)".

HINT: If a leak is detected during this leak test, or if DTCs P0441, P0442 and P0446 were output simultaneously, conduct a leak test again after repair. If no leak is found at this time, the EVAP system is recovered to normal.

Wiring Diagram:

CONFIRMATION READINESS TEST

TEST

First Trip Procedure

a. The vehicle must be cold and the ambient temperature must be approximately between 50 to 95°F.
b. The Intake Air Temperature (IAT) and the Engine Coolant Temperature (ECT) sensors indicate almost the same value.

c. Clear the DTCs.
- Disconnect the battery cable or remove the EFI and ETCS fuses more than 60 seconds.
- READINESS TESTS will show INCMPL (incomplete).

d. Drive the vehicle on a freeway. Write down the initial status of the READINESS TESTS. As each Readiness Test passes EVAP evaluation monitors, its status will change to COMPL (complete). This procedure may take approximately 20 minutes or more.

NOTE: Do not shut off the engine - the results will be invalid.

Pass Condition - No Problem Found by the ECM

If the EVAP evaluation monitor shows COMPL, go to the NON-CONTINUOUS TESTS screen.
- Enter the following menus: ADVANCED OBD II / ONBOARD TESTS / NON-CONTINUOUS TESTS.

NOTE: Do not shut off the engine - the results will be invalid.

- To get there, go to Advanced OBD II, Onboard Tests, Non-continuous Tests.
- If all of the tests in the "Time $02" category show "Pass", the EVAP evaluation monitor detected no problems.

Fail Condition - Problem Detected by the ECM

If the EVAP evaluation monitor shows INCMPL, go to the NON-CONTINUOUS TESTS screen.

1. If all tests show "Pass", one of the following may have occurred:
- The EVAP evaluation monitor did not operate.
- The EVAP evaluation monitor did not finish its tests.
- The ECM has withheld judgement.

2. If one or more of the tests in the time $02 category show "Fail", the EVAP evaluation monitor did operate and the ECM detected a problem.

3. Go to the CONTINUOUS TESTS screen. This is the only place DTC's are listed for the first trip.

NOTE: The DTCs listed may not be valid. A second trip is needed to confirm listed DTCs.

Second Trip Procedure

e. The vehicle must be cold, and the ambient temperature must be approximately between 50 to 95°F.
f. Go to the READINESS TESTS screen.
g. Drive the vehicle on a freeway. Write down the initial status of the READINESS TESTS. This procedure may take approximately 20 minutes or more.

NOTE: Do not shut off the engine - the results will be invalid.

h. If the READINESS TESTS change to COMPL, the EVAP evaluation monitor has operated. Check for any stored DTCs.
- If a DTC was stored, the problem has been detected and confirmed by the ECM.
- If no DTC was found, the EVAP monitor operated but no problem was detected.

INSPECTION PROCEDURE

HINT:
- If DTC P0441 (Purge Flow), P0446 (CCV), P0451, P0452 or P0453 (Evaporative Pressure Sensor) is output with DTC P0442 or P0456, first troubleshoot DTC P0441, P0446, P0451, P0452 or P0453.
If no malfunction is detected, troubleshoot DTC P0442 or P0456 next.
- Ask the customer if the following situations occurred.
1. When the MIL illuminated, if the fuel tank cap was loose and if it was then tightened.
2. When refueling, if the fuel tank cap was loose.

If the fuel tank cap was loose, that is why the DTC was stored.
If the fuel tank cap was loose or if the customer cannot remember, troubleshoot according to the procedures.

- 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.
- If the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.