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 vapor lines.
- The fuel cap.
- The evaporative emission canister.
- The purge lines.
- The EVAP purge solenoid.

The evaporative leak detection diagnostic strategy is based on applying the vacuum to the EVAP system and monitoring the vacuum decay. The VCM monitors the vacuum level via the fuel tank vacuum sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid turn ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or a malfunctioning EVAP purge solenoid is indicated. The following conditions can cause this problem:

- A disconnected or malfunctioning fuel tank pressure sensor.
- A missing, malfunctioning, improperly installed, or loose fuel cap.
- A disconnected, damaged, pinched or blocked EVAP purge line.
- A disconnected or damaged EVAP vent hose.
- A disconnected, damaged, pinched, or blocked fuel tank vapor line.
- A disconnected or malfunctioning EVAP purge solenoid.
- A disconnected or malfunctioning EVAP vent solenoid.
- An open ignition feed circuit to the EVAP vent or purge solenoid.
- A damaged EVAP canister.
- A leaking fuel sender assembly O-ring.
- A leaking fuel tank or fuel filler neck.

Conditions for Running the DTC

- No active MAP sensor DTCs.
- No active TP sensor DTCs.
- No active VS DTCs.
- No active O2 sensor DTCs.
- No active ECT sensor DTCs.
- No active IAT sensor DTCs.
- DTC P0125 not active.
- The system voltage is between 10-17 volts.
- The Fuel Level is greater than 12.5 % and 87 %.
- The ECT is between 4-30°C (39-86°F).
- The IAT is between 4-30°C (39-86°F).
- The cold start temperature difference (ECT minus IAT) is less than:
- 1.5°C (35°F) when the IAT is greater than the ECT or
- 8°C (46°F) when the ECT is greater than the IAT.
- The BARO is greater than 73 kpa.

Conditions for Setting the DTC

The EVAP system is unable to generate a vacuum greater than a calibrated value over a specified period of time.

Action Taken When the DTC Sets

- The VCM illuminates the MIL during the second consecutive drive cycle in which the diagnostic reports a fail.
- The VCM will set the DTC and records the operating conditions at the time the diagnostic fails. The VCM stores the failure information in the scan tools Freeze Frame and Failure Records.

Conditions for Clearing the MIL or DTC

- The MIL will turn OFF after one ignition cycle in which the diagnostic runs without a fault.
- The Freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.
- A scan tool can clear the DTC(s).

Diagnostic Aids

Important: An accurate indication of fuel level is required for the VCM to properly pass or fail this DTC. Always diagnose fuel level sensor DTC's before performing this DTC's diagnostic table. Always check for fuel level sensor DTC's stored in history.

Check for the following conditions:

- A loose, missing, damaged, or improperly installed fuel cap.
- Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings.
- A loose, damaged or misaligned fuel filler tube or fuel filler vent hose.
- A cracked or punctured EVAP canister.
- A damaged or disconnected source vacuum line, EVAP purge line, vent hose or fuel tank vapor line.
- Incorrectly routed or defective EVAP system vacuum and vapor lines.
- A poor connection at the VCM: Inspect the harness connectors for the following conditions:
- Backed out terminals.
- Improper mating.
- Broker locks.
- Improperly formed or damaged terminals.
- Poor terminal to wire connection.
- A damaged harness: Inspect the wiring harness to the EVAP vent solenoid 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 or not restricted.

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

Test Description

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

3. Inspect the service port. Make sure that the dust cap and valve core is not loose or damaged. If the service port is suspect of leakage use the following procedure:

- Disconnect the purge line from the EVAP Purge solenoid valve.
- Connect a hand vacuum pump to the service port by placing the hose/adaptor over the unthreaded end portion of the service port.
- Apply vacuum to 5 in. Hg. If the vacuum does not hold replace the entire EVAP Purge line which includes the service port.

4. If the vehicle passes the Service Bay Test then an intermittent leak or restriction had occurred. Check the fuel tank cap for a possible loose or off condition that may have caused this DTC to set.

- If the Service Bay Test can not be run, proceed to Step 5. If a fault is not currently present the diagnostic table steps will return you to Step 3.

9. Refer to the information supplied with the EVAP pressure/purge diagnostic cart on proper setup and adjustment procedures.
10. With pressure applied it may be necessary to disconnect the EVAP lines at the components to verify that a line or component is not restricted. A restriction would prevent a vacuum (or the Step 9 test pressure) from forming in the fuel tank.
22. An EVAP Pressure sensor that does not correctly respond to vacuum (or pressure) will cause this DTC to set.

- The EVAP Pressure Sensor monitors a range from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).