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P0440

DTC P0440 Evaporative Emission (EVAP) System




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 hoses
- The fuel vapor lines
- 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 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 valve will turn OFF, sealing the system. DTC P0440 will set because the PCM is not detecting the expected vacuum. This can be caused by the following components with the conditions listed below:
- The fuel cap for the following conditions:
- Missing
- Malfunctioning
- Incorrect

- The fuel tank pressure sensor for the following conditions:
- Disconnected
- Malfunctioning

- The EVAP purge line for the following conditions:
- Disconnected
- Damaged
- Pinched
- Blocked

- The EVAP vent hose for the following conditions:
- Disconnected
- Damaged

- The fuel tank vapor line for the following conditions:
- Disconnected
- Damaged
- Pinched
- Blocked

- The EVAP canister purge solenoid valve for the following conditions:
- Disconnected
- Malfunctioning

- The EVAP vent solenoid for the following conditions:
- Disconnected
- Malfunctioning

- An open ignition positive voltage circuit to the following components:
- EVAP vent valve
- Purge solenoid

- A damaged EVAP canister

- A leaking fuel sender assembly O-ring

- A leak in the following items:
- Fuel tank
- Fuel filler neck

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 5° C and 29° C (41° F and 84° F) at engine start up.
- The engine coolant temperature is between 5° C and 29° C (41° F and 84° 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 7° C (12° F) more than the Intake Air Temperature at start up.
- The fuel tank level is between 15 percent and 55 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.
- A history DTC stores.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF after one ignition cycle in which the diagnostic runs a pass.
- Freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.

Diagnostic Aids
Check for the following conditions:
- A missing, loose, or damage fuel cap.
- Missing or damaged O-rings at the EVAP canister fuel vapor fittings and the purge line fittings
- A cracked EVAP canister
- Damaged or disconnected source vacuum line, EVAP purge line, vent hose or fuel tank vapor line
- A poor connection at the PCM: Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals.
- Damaged harness: Inspect the wiring harness to the EVAP vent solenoid, the EVAP purge solenoid, and the fuel tank pressure sensor for an intermittent open or short circuit.
- A kinked, pinched or plugged vacuum source, EVAP purge, or fuel tank vapor line. Verify that the lines are not restricted.

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

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.

Steps 1 - 4:




Steps 5 - 6:




Steps 7 - 9:




Steps 10 - 12:




Steps 13 - 15:




Steps 16 - 18:




Steps 19 - 20:




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 the malfunction occurred. The scan tool stores this data for later reference.
4. If a vent solenoid or 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 P0440.
5. This step checks the fuel tank pressure sensor at the ambient pressure.
6. This step determines whether or not the EVAP system is sealed sufficiently in order to be pressurized. If not, you must locate and correct the large leak before continuing with the diagnosis.
7. This step verifies that the fuel tank pressure sensor accurately reacts to the EVAP system pressure changes.
10. This step checks for a stuck closed EVAP canister purge valve.
11. This step ensures that a sufficient source vacuum is present at the EVAP canister purge valve.
18. This step insures a proper system integrity.

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