P1441

DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge




Circuit Description
The evaporative system includes the following components:
- The fuel tank
- The EVAP vent solenoid
- The fuel tank pressure sensor
- The fuel pipes and the hoses
- The fuel vapor tines
- The fuel cap
- The EVAP canister
- The purge lines
- The EVAP canister purge solenoid valve
- The EVAP service port

The evaporative emission system is checked by applying vacuum to the EVAP system and by monitoring for a vacuum decay. The PCM monitors the vacuum level through the fuel tank pressure sensor signal. At an appropriate time, the EVAP canister purge solenoid valve and the EVAP vent solenoid are turned ON, allowing the engine to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP canister purge solenoid valve is turned OFF, sealing the system.

The EVAP canister purge solenoid valve controls the amount of engine vacuum applied to the EVAP canister. The Powertrain Control Module (PCM) supplies a ground in order to energize the solenoid valve (purge ON). The EVAP canister purge solenoid valve control is Pulse Width Modulated (PWM) from 8 to 16 cycles per second. The duty cycle (pulse width) is determined by the engine operating conditions including the following items:
- Engine load
- Throttle Position
- Engine coolant temperature
- Ambient temperature

The system checks for conditions that cause the EVAP system to purge continuously by commanding the EVAP canister purge solenoid valve OFF. 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:
- A leak in the EVAP canister purge solenoid valve
- The following lines may be switched at the EVAP canister purge solenoid valve:
- EVAP purge
- Engine vacuum
- The EVAP canister purge solenoid valve driver circuit is grounded

If any of these conditions are present, DTC P1441 will set.

Conditions for Running the DTC
- No active MAP DTC's
- No active IAT DTC's
- No active ECT DTC's
- No active TP DTC's
- No active Oxygen Sensor DTC's
- No active Fuel Tank Pressure DTC's
- No active VSS DTC's
- No active PCM Memory DTC's
- The BARO is more than 75 kPa.
- The intake air temperature is between 4° C and 30° C (39° F and 86° F) at engine start up.
- The engine coolant temperature is between 4° C and 30° C (39° F and 86° F) at engine start up.
- The Intake Air Temperature is not more than 1° C (2° F) more than the Engine Coolant Temperature at start up.
- The Engine Coolant Temperature is not more than 8° C (14° F) more than the Intake Air Temperature at start up.
- The fuel tank level is between 15 percent and 85 percent.
- The TP sensor is between 7 percent and 35 percent.

Conditions for Setting the DTC
The EVAP system is unable to detect vacuum during the diagnostic test.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The PCM will record the operating conditions at the time that the diagnostic fails The Freeze Frame and Failure Records buffers will store this information.
- The EVAP purge function is disabled until the diagnostic passes.
- A history DTC stores.

Conditions for Clearing the MIL/DTC
- The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs a pass.
- A history DTC will clear after 40 consecutive warm up cycles without a malfunction.
- A scan tool can clear the DTCs.

Diagnostic Aids
Although this DTC is considered a type A diagnostic, the DTC 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:
- A poor connection at the PCM: Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- A damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, connect the EVAP pressure/purge cart to the EVAP service port, pressurize the EVAP system to 10 in. H2O and observe the Fuel Tank Vacuum Pressure display on the scan tool while moving the connectors and the wiring harnesses related to the EVAP canister purge valve. A sudden change in the display will indicate the location of the fault.
- An incorrect vacuum line routing: Verify that the source vacuum line routing to the EVAP canister purge valve is correct and that the EVAP purge and source vacuum lines to the EVAP canister purge valve are not switched.

Check for charcoal particles. Refer to EVAP System Cleaning before starting repairs.

Steps 1 - 3:

Steps 4 - 5:

Steps 6 - 10:

Steps 11 - 13:

Test Description
The numbers below refers to the step numbers on the Diagnostic Table.
1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when this DTC sets. The scan tool stores this data for later reference.
3. If an EVAP 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.
4. This step checks the fuel tank pressure sensor at the ambient pressure.
6. This step verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
8. If the EVAP purge and engine vacuum lines are switched at the EVAP canister purge valve, the solenoid valve will leak vacuum.
11. This step duplicates the Powertrain On-Board Diagnostic test.