[Previous][Next]
DTC P04EC: Evaporative Emission Control System Leak Detected (gross leak from fuel tank)
 
 
 
 
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 evaporative purge system leakage check pressure subtracted from the barometric pressure is following pressure or less: the barometric pressure - the second reference pressure in parentheses times 0.2.
  • The canister leakage check pressure subtracted from the barometric pressure is following pressure or more: the third reference pressure subtracted from the barometric pressure.
Or
  • The ratio of canister pressure with bypass valve closed to canister pressure with bypass valve open is specified value or more.
  • The canister pressure subtracted from the barometric pressure is specified pressure or more while the bypass valve is closed.
 
 
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:)
  • Fuel tank seal failed.
  • Purge line or vapor line seal failed.
  • Loose fuel cap.
  • Evaporative leak check module circuit harness damage or connector damage.
  • Evaporative emission purge solenoid circuit harness damage or connector damage.
  • ECM failed.
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), check the evaporative emission system monitor test.
(1) Carry out an evaporative emission system monitor. Refer to Evaporative Emission System Monitor Test .
(2) Check the item 193, EVP Leak from Tank in the data list.
(3) Turn off the power supply mode of the electric motor switch.
Is the data list "Normal"?
The evaporative emission system is working properly at this time. Explain to the customer that an improperly tightened fuel cap can cause the MIL to illuminate. Return the vehicle to the customer.
Go to Step 2.
 
STEP 2. 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 3.
Repair the connector(s) or wiring harness. Then go to Step 16.
 
STEP 3. 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 4.
Repair the connector(s) or wiring harness. Then go to Step 16.
 
STEP 4. 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 5.
Repair the connector(s) or wiring harness. Then go to Step 16.
 
STEP 5. Check of harness damage in power supply line between MFI relay connector and evaporative emission purge solenoid connector.
Is the harness wire in good condition?
Go to Step 6.
Repair the connector(s) or wiring harness. Then go to Step 16.
 
STEP 6. Check of harness damage in PURG line between evaporative emission purge solenoid connector and ECM connector.
Is the harness wire in good condition?
Go to Step 7.
Repair the connector(s) or wiring harness. Then go to Step 16.
 
STEP 7. Check the evaporative emission purge solenoid for leaks.
Refer to GROUP 17, Emission Control - Evaporative Emission Control System - Evaporative Emission Purge Solenoid Check .
Does the evaporative emission purge solenoid hold pressure?
Go to Step 8.
Replace the evaporative emission purge solenoid. Then go to Step 16.
 
STEP 8. Check for leaks in evaporative emission hose A, chamber and hose B.
Use a hand vacuum pump to check hose A, chamber and hose B.
Do the hoses and chamber hold vacuum?
Go to Step 9.
Replace any damaged hose. Then go to Step 16.
 
STEP 9. Check for leaks in evaporative emission hose C.
Use a hand vacuum pump to check hose C.
Does hose C hold vacuum?
Go to Step 10.
Replace any damaged hose. Then go to Step 16.
 
STEP 10. Check for leaks in evaporative emission hose D.
Use a hand vacuum pump to check hose D.
Does hose D hold vacuum?
Go to Step 11.
Replace any damaged hose. Then go to Step 16.
 
STEP 11. Check for leaks in evaporative emission hose E.
Use a hand vacuum pump to check hose E.
Does hose E hold vacuum?
Go to Step 12.
Replace any damaged hose. Then go to Step 16.
 
STEP 12. Check the fuel tank solenoid valve for leaks.
Refer to GROUP 17, Emission Control - Evaporative Emission Control System - Fuel Tank Solenoid Valve Check .
Does the fuel tank solenoid valve hold pressure?
Go to Step 13.
Replace the fuel tank solenoid valve. Then go to Step 16.
 
STEP 13. Check for leaks in evaporative emission hoses F, G and H.
(1) Drain the fuel from the fuel tank.
(2) Use a hand vacuum pump to check each hose F, G and H.
Does the hose hold vacuum?
Go to Step 14.
Replace any damaged hose. Then go to Step 16.
 
STEP 14. Check for leaks in the fuel tank.
(1) Visually check for cracks or other leaks in the fuel tank.
noteCarefully check the fuel pump module and the fuel tank differential pressure sensor installation in the fuel tank.
(2) Connect the evaporative emission system pressure pump (Miller number 6872A) to the fuel filler hose.
(3) Plug the hose and the nipple shown in the illustration.
noteIf these items are not securely plugged now, the fuel could leak in the next step.
(4) Pressurize the fuel tank with the evaporative emission system pressure pump.
(5) In the pressurized state, check for leaks by applying a soapy water solution to each section and look for bubbles.
Are any leaks found?
: Repair or replace the leaked parts and check again that there are no leaks. Then reinstall the fuel tank. Then go to Step 16.
: Replace the fuel tank. Go to Step 16.
When there is no leak, reinstall the fuel tank. Then go to Step 15.
 
STEP 15. Replace the bypass valve (integrated in evaporative emission canister).
(1) Replace the bypass valve (integrated in evaporative emission canister).
(2) Carry out an evaporative emission system monitor. Refer to Evaporative Emission System Monitor Test .
(3) Check the item 193, EVP Leak from Tank 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 16.
 
STEP 16. 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 P04EC set?
Repeat the troubleshooting.
The procedure is complete.