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DTC P04EF: Evaporative Emission Control System Leak Detected (0.5mm leak from evaporative emission canister)
 
 
 
 
TECHNICAL DESCRIPTION
  • During the key-off evaporative leakage monitoring, by comparing the reference pressure for which the reference space in the evaporative leak check module with the reference orifice is depressurized and the value for which the evaporative emission control system is depressurized, detect the leak in the evaporative emission control system.
  • Determine whether it is a 0.5 mm leak or gross leak according to the depressurized value of the evaporative emission control system.
  • By opening/closing the fuel tank solenoid valve and bypass valve, identify the leak on the fuel tank side and evaporative emission canister side.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Evaporative leak check monitor is performed by ELCM operation during key-off - after 5 to 8.5 hour soak. ECM makes a comparison between evap system negative pressure and 0.02 inch leak negative pressure.
 
 
MONITOR EXECUTION
  • Once per driving cycle.
 
 
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Evaporative emission purge solenoid monitor
  • Bypass valve monitor
  • Fuel tank solenoid valve monitor
  • Switching valve monitor
  • Canister pressure sensor monitor
  • Manifold absolute pressure sensor monitor
  • Fuel tank pressure sensor monitor
  • Fuel tank differential pressure sensor monitor
  • Barometric pressure sensor/Manifold absolute pressure correlation
  • Barometric pressure sensor monitor
  • Fuel level sensor monitor
  • Engine off timer monitor
  • Controller area network (CAN) monitor
Sensor (The sensors below are determined to be normal)
  • Engine coolant temperature sensor
  • Intake air temperature sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart (Monitor Sequence)
 
 
Check Conditions
  • Power supply mode of electric motor switch is OFF.
  • 12V starter battery positive voltage is 11 volts or higher.
  • Engine coolant temperature is higher than 4°C (39°F) and lower than 35°C (95°F).
  • Intake air temperature at ECM wake-up is higher than 4°C (39°F) and lower than 35°C (95°F).
  • ECM is woken up in 5, 6 or 8.5 hours since the power supply mode of electric motor switch was OFF.
  • Barometric pressure is 76 kPa (22.4 in.Hg) or higher.
  • Fuel level is 85 % or less.
  • Fuel tank pressure at ECM wake-up is less than 19.96 kPa (5.89 in.Hg) or more than 40.00 kPa (11.81 in.Hg).
Judgment Criteria
  • The canister leakage check pressure subtracted from the barometric pressure is more than following pressure: the barometric pressure - the third reference pressure in parentheses times 0.2.
  • The canister leakage check pressure subtracted from the barometric pressure is less than following pressure: the third reference pressure subtracted from the barometric pressure.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
 
 
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
  • Malfunction of the evaporative emission canister seal.
  • Malfunction of the evaporative leak check module seal.
  • Vent pipe is clogged.
  • Evaporative leak check module circuit harness damage or connector damage.
  • Bypass valve circuit harness damage or connector damage.
  • ECM failed.
 
 
DIAGNOSIS
STEP 1. Check of harness damage in COVB line between MFI relay connector and evaporative leak check module connector.
Is the harness wire in good condition?
Go to Step 2.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 2. Check of harness damage in EVB, ECOV, EVSE, EVS and EVSS line between evaporative leak check module connector and ECM connector.
Is the harness wire in good condition?
Go to Step 3.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 3. Check of harness damage in E line between evaporative leak check module connector and ground.
Is the harness wire in good condition?
Go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 4. Check of harness damage in power supply line between MFI relay connector and bypass valve connector.
Is the harness wire in good condition?
Go to Step 5.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 5. Check of harness damage in VAPR line between bypass valve connector and ECM connector.
Is the harness wire in good condition?
Go to Step 6.
Repair the connector(s) or wiring harness. Then go to Step 8.
 
STEP 6. Check clogging of the evaporative leak check module air inlet and vent pipe
(1) Disconnect the hose of the evaporative leak check module air inlet, and visually check whether the air inlet is blocked by foreign matters etc.
(2) Mount the hand vacuum pump on the side of the hose disconnected at (1).
  • When negative pressure is applied with the hand vacuum pump, check that there is ventilation and no clogging.
Is the vent pipe in good condition?
Go to Step 7.
Repair it. Then go to Step 8.
 
STEP 7. Replace the evaporative emission canister.
(1) Replace the evaporative emission canister.
(2) Carry out an evaporative emission system monitor. Refer to Evaporative Emission System Monitor Test .
(3) Check the item 194, EVP Leak from Canister in the data list.
(4) Turn off the power supply mode of the electric motor switch.
Is the data list "Normal"?
The inspection is complete.
Replace the ECM (Refer to Removal and Installation ). Then go to Step 8.
 
STEP 8. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P04EF set?
Repeat the troubleshooting.
The procedure is complete.