P0442
System Digram:
TECHNICAL DESCRIPTION
- To judge if there is leak in the fuel system, PCM measure the change of the pressure inside the fuel tank.
- The PCM turns ON the evaporative emission ventilation solenoid to shut off the evaporative emission canister outlet port.
- Then the evaporative emission purge solenoid is driven to set the fuel system into a negative pressure.
- When the fuel system develops a vacuum of 2 kPa (0.29 psi), the evaporative emission purge solenoid is turned "OFF" and the fuel system vacuum is maintained at 2 kPa (0.29 psi).
- The PCM determines if there is leak in the fuel system by measuring the change of vacuum inside the fuel tank.
- The test is stopped when fuel vapor pressure is judged as too high.
DTC SET CONDITIONS
Test Conditions
A. At Start up
- Intake air temperature is 30°C (86° F) or less when the engine is started.
- The engine coolant temperature is 30°C (86° F) or less when the engine is started.
B. For Test to Run
- With in 16 minutes after the engine is started.
- Engine coolant temperature is higher than 60 °C (140° F).
- Engine speed is 1,600 r/min or more.
- Power steering pressure switch: "OFF."
- Barometric pressure is above 76 kPa (11 psi).
- Volumetric efficiency is between 25 and 80 percent.
- Vehicle speed is 30 km/h (18.7 mph) or more.
C. For Test to Stop
- Intake air temperature is less than 5°C (41° F).
- Engine coolant temperature is higher than 60 °C (140°F).
- When the evaporative emission purge solenoid and the evaporative emission ventilation solenoid are closed, the pressure rises within 451 Pa (0.065 psi).
- The pressure fluctuation width is less than 647 Pa (0.094 psi).
Judgment Criteria
- Internal pressure of the fuel tank has changed more than 981 Pa (0.142 psi) in 20 seconds after the tank and vapor line were closed.
NOTE: The monitoring time depends on the fuel level and the temperature in the fuel tank (75 - 125 seconds.).
Test Conditions
A. At Start Up
- Intake air temperature is 30°C (86°F) or less when the engine started.
- The engine coolant temperature is 30°C (86°F) or less when the engine started.
B. For Test to Run
- Engine coolant temperature is higher than 60°C (140°F).
- Engine speed is 1,600 r/min or more.
- Power steering pressure switch: "OFF".
- Barometric pressure is above 76 kPa (11 psi).
- Volumetric efficiency is between 25 and 80 percent.
- Vehicle speed is 10 km/h (6.2 mph) or less.
- Closed throttle position switch: "ON" <3.0L Engine>.
- Throttle valve is closed <3.5L Engine>.
- Under the closed loop air/fuel ratio control.
- Fuel temperature is lower than 30°C (86°F).
C. For Test to Stop
- Intake air temperature is less than 5°C (41° F).
- Engine coolant temperature is higher than 60°C (140° F).
- When the evaporative emission purge solenoid and the evaporative emission ventilation solenoid are closed, the pressure rises within 451 Pa (0.065 psi).
- The pressure fluctuation width is less than 647 Pa (0.094 psi).
Judgement Criteria
- Internal pressure of the fuel tank has changed more than 647 Pa (0.094 psi) in 20 seconds after the tank and vapor line were closed (when the fuel gauge unit output voltage is lower than 1.25 volts).
or
- Internal pressure of the fuel tank has changed more than 785 Pa (0.114 psi) in 20 seconds after the tank and vapor line were closed (when the fuel gauge unit output voltage is lower than 2.5 volts).
or
- Internal pressure of the fuel tank has changed more than 1,076 Pa (0.156 psi) in 20 seconds after the tank and vapor line were closed (when the fuel gauge unit output voltage is lower than 3.75 volts).
or
- Internal pressure of the fuel tank has changed more than 1,764 Pa (0.256 psi) in 20 seconds after the tank and vapor line were closed (when the fuel gauge unit output voltage is lower than 5 volts).
NOTE: The monitoring time depends on the fuel level and the temperature in the fuel tank (90 - 195 seconds).
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Loose fuel cap.
- Fuel cap relief pressure is incorrect.
- Evaporative emission canister seal is faulty.
- Fuel overflow limiter valve failed.
- Fuel tank, purge line or vapor line seal failed.
- Evaporative emission ventilation solenoid failed.
OVERVIEW OF TROUBLESHOOTING
- To determine the cause of DTC P0442, a performance test is needed. The performance test uses a mechanical vacuum gauge and scan tool MB991502 set on the fuel tank differential pressure sensor (TANK PRES SNER 73). The mechanical gauge reading is used to verify scan tool MB991502 reading.
A comparison of the mechanical gauge to scan tool MB991502 determines the problem in the system.
- Prior to doing the performance test, several simple inspections are needed to exclude some possibilities of the symptom.
DIAGNOSES
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
In this procedure, scan tool MB991502 should be used in the metric mode (showing the value in kPa). If not, set scan tool MB991502 by selecting the "System Setup" at the main menu.
STEP 1. Evaporative Emission System Pressure Test using pressure pump.
1. Disconnect hose H from the evaporative emission ventilation solenoid side, and plug the hoses from which the hoses have been disconnected.
2. Confirm that the evaporative emission system pressure pump (Miller number 6872A) is operating properly. Perform the self-test as described in the manufacturer's instructions.
3. Connect an evaporative emission system pressure pump to the fuel filler neck.
4. Pressure test the system to determine whether any leaks are present.
5. Carry out the pressure test with the evaporative emission system pressure pump (Miller number 6872A).
CAUTION: Do not shake the vehicle during the test.
a. Carry out the test at the following conditions.
- Verify the vehicle fuel tank is full of fuel. Add fuel as required.
- Test with the environmental temperature at 32°C (90°F) or less.
- Test with the fuel temperature at 32°C (90°F) or less.
b. Set pressure/hold valve to OPEN, and set evaporative emission ventilation solenoid to CLOSED.
c. Turn pump timer ON, and watch the gauge.
d. Cycle the pressure/hold valve until the gauge reads 14 inches H2O with the valve closed. Note time and pressure.
e. Turn the pump timer OFF.
- If Pressure does not drop more than six inches (to 8 inches H2O on the gauge) in two minutes, the system is OK.
- If Pressure drop more than six inches (below 8 inches H2O on the gauge) in two minutes, go to Step 2.
f. Switch evaporative emission ventilation solenoid to OPEN.
g. Disconnect pump from vehicle if testing is complete. Reconnect system components.
STEP 2. Check the fuel overflow limiter valve plunger and flapper door operation.
NOTE: The fuel overflow limiter valve plunger opens and closes in sequence with the flapper door and fuel overflow limiter valve plunger.
When the fuel gun is inserted in the fuel filler neck and the flapper door is opened, the fuel overflow limiter valve plunger will close. (The fuel overflow limiter valve plunger will move to the top of the neck)
When the fuel cap is closed, the fuel cap pushes the fuel overflow limiter valve plunger and the fuel overflow limiter valve plunger opens.
If the flapper door or fuel overflow limiter valve plunger does not operate correctly, the fuel overflow limiter valve plunger and fuel cap will interfere, and the fuel cap will not close completely This can cause DTC P0442 to occur.
1. Remove the fuel cap.
2. Push the flapper with an ornament remover, etc., to activate the valve.
NOTE: The fuel overflow limiter valve plunger moves upward when the flapper is pushed.
3. Tighten the fuel cap until three clicks are heard.
4. Remove the fuel cap again, and with the fuel overflow limiter valve plunger pushed in, measure the projection amount.
5. Confirm that the distance from the end of the fuel tank filler neck to the end of the fuel overflow limiter valve plunger is 28 mm (1.1 inches) or more.
If the fuel overflow limiter valve plunger does not return completely [when less than 28 mm (1.1 inches)], replace the fuel tank filler neck, completely tighten the fuel cap and perform OBD-II drive cycle.
If the fuel overflow limiter valve plunger has completely returned [when 28 mm (1.1 inches) or more], completely tighten the fuel cap and go to Step 3.
STEP 3. Confirm the fuel gauge unit operation.
1. Remove the fuel tank.
(Refer to Fuel Tank.)
2. Remove the fuel gauge unit from the fuel tank and inspect the fuel gauge unit.
(Refer to Combination Meter.)
If faulty, replace the fuel gauge unit, install the fuel tank, and perform OBD-II drive cycle.
If normal, go to Step 4.
STEP 4. Check the fuel temperature sensor.
When the resistance value between the sensor terminals is measured under two or more temperature conditions, the resistance value should be close to the values shown in the graph.
NOTE: The temperature conditions when testing should not exceed the range of the characteristic curve in the graph. If faulty, replace the fuel gauge unit, install the fuel tank, and perform OBD-II drive cycle.
If normal, install the fuel gauge unit and fuel tank, and go to Step 5.
STEP 5. Check the evaporative emission ventilation solenoid using the scan tool MB991502. (Actuator test item 29)
1. Turn the ignition switch to "ON" position, and disconnect the hose H from the evaporative emission ventilation solenoid side.
2. Connect the hand vacuum pump to the nipple of the evaporative emission ventilation solenoid from which the hoses have been disconnected.
3. Drive the evaporative emission ventilation solenoid with the scan tool MB991502 actuator test, and confirm that the vacuum does not fluctuate when the vacuum is applied with the hand vacuum pump.
If the evaporative emission ventilation solenoid operates correctly and the applied vacuum does not fluctuate, go to Step 1.
If the evaporative emission ventilation solenoid operates correctly, but the vacuum is not maintained, replace the evaporative emission ventilation solenoid, and then go to Step 1.
If the evaporative emission ventilation solenoid does not operate, refer to the evaporative emission ventilation solenoid trouble code DTC P0446.
STEP 6. Pressure test for evaporator line from hose I to hose N and hose G.
1. Disconnect hose G from the evaporative emission canister side, and plug the hose from which the pipes have been disconnected.
2. Perform the pressure test again. If no leaks are indicated, go to Step 7. If a leak is indicated, go to Step 9.
STEP 7. Check for leaks in the evaporator line from hose B to hose F and hose H.
The leakage test with a hand vacuum pump on each hose from hose B to hose F and hose H.
If the location of the leak is pinpointed, replace that hose, and go to Step 1.
If the location of the leak cannot be pinpointed, go to Step 8.
STEP 8. Check for leaks in the evaporative emission canister.
1. Connect a hand vacuum pump to the vent nipple of the evaporative emission canister.
2. Plug the other two nipples or loop a hose between the other nipples.
3. Apply a vacuum with the hand vacuum pump and confirm that the applied vacuum does not fluctuate.
If the vacuum does not fluctuate, install the fuel tank. Then go to Step 1.
If the applied vacuum fluctuates, replace the evaporative emission canister, install the fuel tank. Then go to Step 1.
STEP 9. Check for leaks in the evaporator line hose G.
The leakage test with a hand vacuum pump on each hose hose G.
If the location of the leak is pinpointed, replace that hose, and go to Step 1.
If the location of the leak cannot be pinpointed, go to Step 10.
STEP 10. Check for leaks in the evaporator line from hose I to hose L.
1. Remove the fuel tank. (Refer to Fuel Tank)
2. The leakage test with a hand vacuum pump on each hose from hose I to hose L.
If the location of the leak is pinpointed, replace that hose, install the fuel tank. Then go to Step 1.
If the location of the leak cannot be pinpointed, go to Step 11.
STEP 11. Check for leaks in the fuel tank.
1. Visually check for cracks and leaks, etc.
NOTE: Carefully check the fuel pump assembly and the inner pressure sensor installation section in the fuel tank.
2. Connect an evaporative emission system pressure pump to the leveling valve nipple.
3. Plug the filler hose, feed pipe, return pipe and rollover valve nipple connected to the fuel tank.
NOTE: If these items are not securely plugged here, the fuel could leak in the next step.
4. Apply pressure with the evaporative emission system pressure pump.
5. In the pressurized state, check for the leak by applying soap water, etc. to each section.
If the leak is at the fuel pump assembly or the inner pressure sensor installation section in the fuel tank: Reassemble the parts, check again that there are no leaks, reinstall the fuel tank, and go to Step 1.
If the leak is at another section:
Go to Step 12.
STEP 12. Visually check for cracks in the fuel tank filler neck.
Visually check for cracks in the fuel tank filler neck.
If cracks are found out, replace the fuel filler neck, and install the fuel tank Then go to Step 1.
If any cracks are not found out, and install the fuel tank. Then go to Step 1.