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 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. An insufficient vacuum level will cause a large leak. This can be caused by the following conditions:
| • | A missing or faulty fuel cap |
| • | A disconnected or faulty fuel tank pressure sensor |
| • | 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 faulty EVAP canister purge valve |
| • | A disconnected or faulty 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 |
Any of the above conditions can set a DTC P0440.
Conditions for Setting the DTC
| • | The BARO is greater 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) greater than the Engine Coolant Temperature at start up. |
| • | The Engine Coolant Temperature is not more than 7°C (12°F) greater than the Intake Air Temperature at start up. |
| • | The fuel tank level is between 26 percent and 74 percent. |
| • | The TP sensor is between 9 percent and 35 percent. |
| • | The EVAP solenoid is at 50 percent PWM within 65 seconds of the engine run time. |
| • | The EVAP system is unable to achieve or maintain vacuum during the diagnostic test. The amount of decay will vary with the fuel level. |
| • | DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134 and P1133 are not set. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) illuminates. |
| • | The PCM records the operating conditions at the time when the diagnostic fails. This information stores in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
| • | The coolant fan turns ON. |
Conditions for Clearing the MIL/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
Although this DTC is considered a type A diagnostic (refer to Powertrain Control Module (Serial Data Communication) ), this DTC acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports that 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.
If a DTC P0460 is set along with an EVAP System DTC, the EVAP DTC cannot be considered valid until you repair and clear DTC P0460.
Check for the following conditions:
| • | A missing or a damaged fuel cap |
| • | Missing or damaged O-rings at the EVAP canister fuel vapor and purge line fittings |
| • | A cracked or a punctured EVAP canister |
| • | A damaged or a disconnected source vacuum line, an EVAP purge line, a vent hose or a fuel tank vapor line |
| • | A poor connection at the PCM. Inspect the harness connectors for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection |
| • | A damaged harness. Inspect the wiring harness to the EVAP vent solenoid, the EVAP canister purge valve and the fuel tank pressure sensor for an intermittent open circuit or a short circuit. |
| • | A kinked, a pinched or a plugged vacuum source, EVAP purge, or fuel tank vapor line. Verify that the lines are not restricted. |
| • | Refer to Carbon Particle Removal from Evaporative Emission System for further procedure. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD 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 fault occurred. The information is then stored on the scan tool for later reference.
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If a vent solenoid or EVAP canister purge valve electrical fault is present, the purge system will not operate correctly. Repairing the electrical fault will very likely correct the condition that set DTC P0440.
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Checks the fuel tank pressure sensor at ambient pressure.
-
Forces the fuel tank pressure sensor to re-zero.
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Determines whether or not the EVAP system is sealed sufficiently to be pressurized. If not, the large leak must be located and corrected before continuing with diagnosis.
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Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
-
Checks for a stuck closed EVAP canister purge valve.
-
Ensures that sufficient source vacuum is present at the EVAP canister purge valve.
-
Insures proper system integrity.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||||||||
2 | Is DTC P0460 also set? | -- | ||||||||
3 |
Was a lose or missing fuel cap found? | -- | ||||||||
Does the purge valve and vent solenoid click when commanded ON and OFF? | -- | |||||||||
Is the Fuel Tank Pressure at the specified value? | 0 in. H2O ( ± 1 H2O) | |||||||||
6 | Has the battery been disconnected? | -- | ||||||||
Disconnect the battery. Is the action complete? | -- | -- | ||||||||
|
Important:: Before continuing with this diagnosis, zero the EVAP Pressure and Vacuum gauges on the EVAP pressure/purge cart J 41413. Also read the temperature variation instructiod. (refer to tool operating instructions).
Can the specified value be achieved? | 5 in. H2O | |||||||||
Is the Fuel Tank Pressure at the specified value? | 5 in. H2O 5 in. (± 2 in. H2O) | |||||||||
10 |
Can vacuum be maintained at the specified value? | 5 in. Hg | ||||||||
11 |
Was a problem found? | -- | ||||||||
Does the EVAP canister purge valve release the vacuum? | 10 in of Hg (34 kPa) | |||||||||
Did the vacuum gauge read greater than the specified value when the throttle was snapped open then closed? | 2500 RPM 10 in. Hg | Go to Diagnostic Aids | ||||||||
14 |
Was a repair necessary? | -- | ||||||||
15 |
Was a repair necessary? | -- | ||||||||
16 |
Is the action complete? | -- | -- | |||||||
17 | Replace the EVAP canister purge valve. Refer to Diagnostic Aids . Is the action complete? | -- | -- | |||||||
18 | Locate and repair the cause of no source of vacuum to the EVAP canister purge valve. Is the action complete? | -- | -- | |||||||
19 | Replace the EVAP vent solenoid. Refer to Diagnostic Aids . Is the action complete? | -- | -- | |||||||
Does the pressure decrease to less than the specified value within 2 minutes? | 15 in. H2O 10 in. H2O | System OK |
