The PCM closes the Canister Close Valve (CCV) at the charcoal canister to seal off the evaporative emission system and then opens purge control valve (PCSV) to generate a vacuum in the fuel tank. After vacuum generation, the PCM measures pressure differential curve in the fuel tank and sets DTC P0442 or P0456 if the vacuum generated within a monitoring period increases above a defined threshold.
If same error code is set in the next driving cycle, the PCM illuminates the MIL.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Monitoring Fuel Tank Pressure Trend after Evacuation | 1. Poor Connector Connection 2. Air leak in PCSV hose 3. Damaged or missing Fuel Filler Cap 4. Defected or damaged Fuel Filler Pipe 5. Leaking, Disconnected or Plugged Fuel Vapor Line 6. Defected PCSV 7. Defected CCV 8. Defected Canister 9. Defected Fuel Tank Pressure Sensor |
Enable Conditions |
•
Engine Coolant Temp.(ECT) higher than 122℉(50℃)
•
Ambient Air Temp. model higher than 14℉(-10℃)
•
Vehicle speed lower than 7.5 mph(12 km/h)
•
Fuel level less than 85%
•
100 sec. after engine start
•
Ambient pressure model more than 10.87 psi(0.75bar)
•
Canister load less than 0.35
•
Minimum canister purge time more than 3 sec. in case of canister load less than or equal to 0.1
•
Minimum canister purge time more than 25 sec. in case of canister load more than or equal to 0.1
•
Engine speed higher lower than 1400 to 2500 RPM depending on ECT
•
Pedal value less than 0.1%(Pedal sensor 1 voltage 0.859V, not pushed at all)
•
Ambient air Temp. learning done one time since engine start(Vehicle speed higher than 15mph (24 km/h) during 150 sec.)
•
60 sec. since last EVAP monitoring test abortion
•
Modeled Ambient Pressure gradient during uphill driving lower than 1.08psi(0.075bar)
•
Battery voltage higher than 10V
•
Fuel sloshing not detected
•
No relevant DTC present | |
Threshold Value |
•
Estimated Leakage Diameter more than or equal to 0.03in(0.81mm) | |
Diagnostic Time |
•
30 sec. | |
MIL On Condition |
•
2 Driving Cycle |
