P0440
P0440-GENERAL EVAP SYSTEM FAILURE
For a complete wiring diagram refer to: Electrical Diagrams
Theory of Operation
The theory behind the Natural Vacuum Leak Detection (NVLD) is adherence to the Ideal Gas Law. Pressure in a sealed vessel will change linearly as a function of the temperature of the gas in the vessel. Even small leaks will allow the pressure in the vessel to come to equilibrium with the atmospheric pressure. The General Evap test runs by commanding purge flow during the leak size test and evaluates the NVLD vacuum switch.
When Monitored
Engine Running after a cold start. Fuel Level greater than 12%. Fuel level below 88%. No NVLD switch during previous engine off time. No NVLD switch close during leak size purge draw. Ambient Temperature between 4°C and 32°C (39°F and 89°F).
Set Condition
The PCM does not see the NVLD switch close during the medium/large leak test. The PCM then will increase the vacuum supply to the EVAP system by increasing flow through the EVAP Purge valve. If the switch does not close with an increase in vacuum an error is detected. Two Trip Fault. Three good trips to turn off the MIL.
Possible Causes
- EVAP PURGE SOLENOID VACUUM SUPPLY
- (Z914) GROUND CIRCUIT OPEN
- (K107) NVLD SWITCH SIGNAL CIRCUIT OPEN
- EVAPORATIVE EMISSION LEAK DETECTION
- NVLD ASSEMBLY
- EVAP PURGE SOLENOID
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION
Ignition on, engine not running.
With a scan tool, read DTCs and record the related Freeze Frame data if any DTC(s) are present.
Whether or not any DTC(s) are present you will want to check the following items which may assist in repairing the customer's complaint successfully.
Check the vehicles repair history.
If the vehicle has a repair history that pertains to the customer's current complaint, review the repair.
Inspect the vehicle for any aftermarket accessories that may have been installed incorrectly.
Check for any service bulletin(s) related to the customer's complaint or DTC(s).
If a service bulletin applies, follow the instructions per the service bulletin.
Choose the following scenario that best applies.
The service bulletin repaired the customer's complaint.
- Testing complete
A DTC is present , no service bulleting applies, or the service bulletin didn't repair the customer's complaint.
- Go to 2
2. ACTIVE DTC
NOTE: If any of the following DTCs are set (P0443, P0452, P0453, P0498 or P0499) diagnose them first before continuing with P0440.
NOTE A loose gas cap could have caused this DTC to set. Make sure the gas cap is tight and in good condition.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes >> Go To 3
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
3. VISUAL AND PHYSICAL INSPECTION
Turn the ignition off.
Perform a visual and physical inspection of the entire Evaporative Emission system.
Check for the following conditions:
- Hoses disconnected or left off
- Holes or cracks
- Loose seal points
- Evidence of damaged components
- Incorrect routing of hoses and tubes
- Fuel Cap left off or bad gasket seal
Were any of the above conditions found?
Yes >> Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Go To 4
4. EVAP VACUUM SUPPLY HOSE INSPECTION
Carefully inspect the Evap Purge Solenoid vacuum supply hose for proper routing to the Throttle Body.
Check for a pinched or plugged hose from the throttle body or intake manifold to the Purge Solenoid.
Make sure the vacuum port at the throttle body or intake manifold is free from any blockage.
Were any problems found?
Yes >> Repair the vacuum supply, hose/tube as necessary.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Go To 5
5. CHECKING EVAP PURGE SOLENOID FUNCTIONALITY
NOTE: To continue testing you will need Miller Tool #8494 Evaporative Emission Leak Detector (EELD).
Connect the red power lead of the EELD to the battery positive terminal and the black ground lead to battery negative terminal.
Disconnect the vacuum hoses vacuum supply hoses at the EVAP Purge Solenoid.
Connect the SMOKE supply tip (black hose) to the "CAN" port on the EVAP Purge Solenoid.
Set the smoke/air control switch to SMOKE.
While still holding the remote smoke/air start button, check to see if smoke is exiting the purge valve. This indicates that there is a leak internal to the purge Valve
Is smoke visible from the EVAP Purge Solenoid?
Yes >> Replace the Evap Purge Solenoid.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Go to 6
6. CHECKING EVAP PURGE SOLENOID FUNCTIONALITY
NOTE: This is an optional method of checking the purge valve for leaks if the EELD is unavailable.
Does the EVAP Purge Solenoid hold vacuum?
Yes >> Go to 7
No >> Replace the Evap Purge Solenoid
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
7. NVLD SWITCH OPERATION
Connect the previously disconnected vacuum hose.
Start the engine.
Allow the engine to idle.
Using the scan tool, perform the NVLD FORCED MONITOR TEST Monitor the NVLD Switch state.
NOTE: As the test runs, the NVLD Switch should go from an OPEN state to a CLOSED state and then return to OPEN when the test is complete.
Did the NVLD Switch operate as described above?
Yes >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Go To 8
8. VERIFY NVLD SWITCH OPERATION
Start the engine
Allow the engine to idle.
Using a scan tool, perform the NVLD FORCED MONITOR TEST for a second time.
While the NVLD FORCED MONITOR TEST is running, open/remove the gas cap.
Monitor the NVLD Switch state.
Did the NVLD Switch go from OPEN to CLOSED?
Yes >> Replace the NVLD Assembly.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Got to 9
9. VERIFY EVAPORATIVE EMISSION LEAK
WARNING: Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases. Keep the test area well ventilated.
Turn the ignition off.
To continue testing you will need Miller Tool #8404 Evaporative Emission Leak Detector (EELD).
NOTE: The fuel tank should have between 20% and 80% of fuel tank capacity to properly test the Evap system.
Connect the red power lead of EELD to the battery positive terminal and the black ground lead to battery negative terminal.
Block the vent hose of the EVAP Canister.
Connect shop air to the EELD.
Set the smoke/air control switch to AIR.
Insert the tester's AIR supply tip (clear hose) into the 0.040 orifice on the tester's control panel.
Press the remote smoke/air start button.
Position the red flag on the air flow meter so it is aligned with the indicator ball.
When the calibration is complete, release the remote button. The EELD flow meter is now calibrated in liters per minute.
Install the service port adapter #8404-14 on the vehicle's service port (if equipped) or install the #8404-ADP into the filter line.
Connect the Air supply hose from the EELD to the service port (if equipped) or to the #8404-ADP adapter. Press the remote button to activate AIR flow.
Compare the flow meter indicator ball reading to the red flag.
ABOVE the red flag indicates a leak present.
BELOW the red flag indicates a sealed system.
Is the indicator ball above the red flag?
Yes >> Go To 10
No >> Go To 12
10. EVAPORATIVE EMISSION LEAK DETECTION
NOTE: A thorough visual inspection of the Evap system hoses, tubes, and connections may save time in your diagnosis. Look for any physical damage or signs of wetness at connections. The strong smell of fuel vapors may aid diagnosis also.
Remove the Air supply hose from the service port or the #8404-ADP adapter.
Connect the SMOKE supply tip (black hose) to the service port (if equipped) or to the #8404-ADP adapter. Set the smoke/air control switch to SMOKE.
NOTE: The flow meter indicator ball will not move at this point.
Press the remote smoke/air start button.
NOTE: Make sure that smoke has filled the EVAP system by continuing to press the remote smoke/air start button, remove the vehicle fuel cap, and wait for the smoke to exit. Once smoke is indicated reinstall the fuel cap.
NOTE: For optimal performance, introduce smoke into the system for an additional 60 seconds; continue introducing smoke at 15 second intervals, as necessary.
While still holding the remote smoke/air start button, use the white light (#8404-CLL) to follow the EVAP system path, and look for the source of the leak indicated by exiting smoke.
If a leak is concealed from view (i.e., top of fuel tank), release the remote smoke/air start button, and use the ultraviolet (UV) black light #8404-UVL and the yellow goggles 8404-20 to look for residual traces of dye that are left behind by the smoke.
The exiting smoke deposits a residual fluid that is either bright green or bright yellow in color when viewed with a UV light.
NOTE: The EVAP System is divided into three zones. A leak fro any of these zones can cause this DTC to set. The lists below specify the possible leak points in that specific zone. For further assistance see the zone identification charts below.
ZONE 1
1. Fuel Cap.
2. Recirculation Check Valve.
3. Vapor Recirculation Line.
4. Signal Vapor Line for FVM.
5. Flow Management Valve.
6. Fuel Tank Canister Vapor Line connection.
7. Fuel Tank Vent (Check valve).
8. Vapor Line to Canister.
9. Flow Control Valve.
10. Control Valve.
11. Liquid Trap.
12. Fuel Tank.
13. Check Valve.
14. Fuel Fill Tube to Tank connector.
15. Fuel Fill Tube.
Damaged or disconnected EVAP system components.
Zone 2
1. Filter.
2. NVLD.
3. Canister Vent Line.
4. Evap Canister.
5. Chassis Purge valve.
6. Fuel Tank to Canister Vapor Line connection.
7. Evap Purge connection.
Zone3
1. Evap Purge Vacuum Line.
2. Connection to Chassis Line.
3. Connection to Canister.
4. Chassis Purge Line.
5. Evap purge Vacuum Line.
6. Connection to Evap Purge Harness.
7. Chassis Evap Purge Line connection to Engine Vacuum.
8. Evap Purge Valve.
9. Service Port.
NOTE: Carefully inspect the vent side of the EVAP Canister. Due to the filtering system in the canister the smoke or dye may or may not be visible. Introducing smoke into the filtered side of the canister may assist in locating the leak.
Select the appropriate response below:
A leak was found at the gas cap or fuel filler tube.
Go to 11
A leak was found in one or more of the EVAP System zones.
If the leak is at a hose connection, remove the hose then reconnect the hose and check for a leak again. All other leaks repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No leaks were detected
Go To 12
11. LEAK AT GAS CAP
Remove the SMOKE supply tip (black hose)from the service port (if equipped) or to the #8404-ADP adapter.
Install gas cap adapter, Miller tool #8382 (1/4 turn cap) or #6922 (screw cap) and 8399* (secondary seal depressor) and repeat test 5.
NOTE: The gas cap adapter is being used as a known good cap.
Was a leak found at the gas cap adapter?
Yes >> Replace the Fuel Filler Tube assembly.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Replace the gas cap.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
12. NVLD ASSEMBLY
Turn the ignition off.
Disconnect the NVLD electrical harness connector. Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
Connect a jumper wire between the (K107) NVLD Switch Signal circuit and the (Z910) Ground circuit in the NVLD electrical harness connector.
Monitor the NVLD Switch state on the scan tool.
Does the Switch change from OPEN to CLOSED when the jumper wire is installed?
Yes >> Replace the NVLD Assembly.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Go To 13
NOTE: Remove the jumper wire before continuing.
13. (Z910) GROUND CIRCUIT OPEN
Turn the ignition off.
Measure the resistance between the (Z910) Ground circuit and ground.
Is the resistance below 5.0 ohms?
Yes >> Go To 14
No >> Repair the open in the (Z914) Ground circuit.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
14. (K107) NVLD SWITCH SIGNAL CIRCUIT OPEN
Disconnect the PCM harness connectors.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K107) NVLD Switch Signal circuit from the NVLD electrical harness connector to the appropriate terminal of the special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 15
No >> Repair the open in the (K107) Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
15. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test