P1441
DTC P1441 EVAPORATIVE EMISSION CONTINUOUS PURGE FLOWSystem Description
The evaporative (EVAP) emission system includes the following components:
- Fuel tank.
- EVAP emission vent solenoid.
- Fuel tank pressure sensor.
- Fuel pipes and hoses.
- Fuel vapor lines.
- Fuel cap.
- EVAP emission canister.
- Purge lines.
- EVAP emission canister purge valve.
- EVAP emission service port.
The EVAP emission system is checked by applying vacuum to the EVAP emission system and monitoring for a vacuum decay. The powertrain control module(PCM)/engine control module (ECM) monitors the vacuum level through the fuel tank pressure sensor signal.
At the appropriate time, the EVAP emission canister purge valve and the EVAP emission vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire EVAP emission system. After the desired vacuum level has been achieved, the EVAP emission canister purge valve is turned OFF, sealing the system. The EVAP emission canister purge valve allows manifold vacuum to purge the canister. The PCM/ECM supplies a ground to energize the solenoid valve (purge ON). The EVAP emission canister purge valve control is Pulse Width Modulated (PWM) or turned ON and OFF several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position (TP), engine coolant temperature (ECT) and ambient temperature. The duty cycle is calculated by the PCM/ECM and the output is commanded when the appropriate conditions have been met.
The system checks for conditions that cause the EVAP emission system to purge continuously by commanding the EVAP emission vent solenoid ON and the EVAP emission canister purge valve OFF (EVAP emission vent solenoid CLOSED, EVAP emission purge PWM 0%).
If the fuel tank vacuum level increases during the test, a continuous purge flow condition is indicated. This can be caused by the following conditions:
- EVAP emission canister purge valve leaking.
- EVAP emission purge and engine vacuum lines switched at the EVAP emission canister purge valve.
- EVAP emission canister purge valve driver circuit grounded.
If any of these conditions are present, DTC P1441 will set.
Conditions for Setting the DTC
- DTC(s) P0106, P0107, P0108, P0113, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0300, P0402, P0404, P0405, P0406, P0443, P0449, P0452, P0453, P0506, P0507, P1130, P1133, P1134, P1404, P1627 and P1640 not set.
- No system voltage malfunction.
- Fuel tank vacuum is greater than 8 inches of H2O for 0.5 second.
- Intake air temperature (IAT) and ECT are between 4 °C and 32 °C (40 °F and 90 °F) at engine start up.
- Barometric Pressure (BARO) is greater than 72 kPa.
- IAT is not more than 1 °C (2 °F) greater than the ECT at start up.
- ECT is not more then 6.25 °C (44 °F) greater than the IAT at start up.
- Fuel tank level is between 15% and 85%.
Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The PCM/ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.
- Coolant fan turns on.
Conditions for Clearing the MIL/DTC
- The MIL will turn off after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 80 consecutive warm-up cycles without a fault.
- DTC(s) can be cleared by disconnecting the battery.
Diagnostic Aids
Although this DTC is considered a type A diagnostic (refer to "Powertrain Control Module/Engine Control Module"), it acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.
Check for the following conditions:
- Poor connection at PCM/ECM. Inspect harness connectors for the following conditions:
- Backed-out terminals
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminal-to-wire connection
- Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, connect the EVAP emission pressure/purge cart to the EVAP emission service port, pressurize the EVAP emission system to 10 inches H2O and observe the Fuel Tank Vacuum Pressure display on the scan tool while moving connectors and wiring harnesses related to the EVAP emission canister purge valve. A sudden change in the display will indicate the location of the fault.
- Incorrect vacuum line routing. Verify that the source vacuum line routing to the EVAP emission canister purge valve is correct and that the EVAP emission purge and source vacuum lines to the EVAP emission canister purge valve are not switched.
- Loose Carbon in the purge solenoid. Blow out the lines and replace the purge canister.
Steps 1 To 5:
Steps 6 To 12:
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
2. If an EVAP emission canister purge valve electrical malfunction is present, the purge system will not operate correctly. Repairing the electrical malfunction will very likely correct the condition that set DTC P1441.
3. Checks the fuel tank pressure sensor at ambient pressure.
5. Forces fuel tank pressure sensor to re-zero.
7. Verifies that the fuel tank pressure sensor accurately reacts to EVAP emission system pressure changes.
9. If the EVAP emission purge and engine vacuum lines are switched at the EVAP emission canister purge valve, the solenoid valve will leak vacuum.
12. Duplicates the On-Board diagnostic test.