P0442
TECHNICAL DESCRIPTION
- To judge if there is leak in the fuel system, ECM
- The ECM
- 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 ECM
- 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 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 500 (41 °F).
- The engine coolant temperature higher than 60 °C (140 °F).
- When the evaporative emission purge solenoid and 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).
- Fuel tank differential pressure sensor output voltage is 1 to 4 V.
Judgment Criteria
- 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.
NOTE: The monitoring time depends on the fuel level and the temperature in the fuel tank (75 - 125 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 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.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "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 Monitor Test using scan tool MB991502.
CAUTION: With this monitor, the ECM
1. Turn the ignition switch to the "ON" position.
2. Erase the DTCs using the scan tool MB991502.
3. Check that the fuel cap is securely closed. (Tighten until three clicks are heard.)
4. Start the engine.
5. Select "System Test," and press the"YES" key.
6. Select "Evap Leak Mon," and press the "YES" key.
7. During the monitor, keep the accelerator pedal at the idling position.
NOTE: If the engine speed does not reach 2,000 r/min during the monitor test, adjustment of the Speed Adjusting Screw may be needed. Refer to Basic Idle Speed Adjustment and adjust to the standard value.
8. keep the engine speed and engine load within the specified range. When the monitor test starts, the "In Progress" item on the scan tool MB991502 will change from "NO" to "YES."
Q: What is displayed on the scan tool MB991507?
"Evap Leak Mon. Completed Test Passed": The evaporative emission system is working properly at this time. Explain to customer that improperly tightened fuel cap can cause MIL to turn on, and return the vehicle.
"Evap Leak Mon. Completed. Test Failed end DTCs Set": A malfunction has been detected during the monitor test. Go to Step 2.
"Evap Lead Mon. discontinued. Retest again from the first": The monitor was discontinued for a certain reason (vehicle speed input from computer, engine speed and engine load deviating from specified range). Turn the ignition switch to the "LOCK" (OFF) position once, and repeat the monitoring from the Step 1.
STEP 2. Pressure test for evaporator line from hose C to hose Q.
1. Remove the module bracket mounting bolts, and disconnect hose G 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 #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.
NOTE: "Pressure test" in this procedure refers to the 1/M240 Simulation Test (8 simple steps) described in the evaporative emission system pressure pump (Miller #6872A) manufacturer's instructions located in the lid of the pump box.
Q: Are there any leaks in the evaporator line?
YES: Go to Step 3.
NO: Go to Step 4.
STEP 3. Check the evaporative emission ventilation solenoid valve using the scan tool MB991502. (Actuator test item 29).
1. Turn the ignition switch to the the "ON" position, and disconnect the hose G 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.
Q: Does the vacuum pump gauge indicate the atmospheric pressure when the evaporative emission purge solenoid is activated?
The evaporative emission purge solenoid valve operates normally, and the vacuum pump gauge reading returns to the atmospheric pressure: Go to Step 1.
The evaporative emission purge solenoid valve operates normally, but the vacuum pump gauge does not indicate the atmospheric pressure: Replace the evaporative emission purge solenoid. Then go to Step 1.
The evaporative emission purge solenoid valve does not operate normally: Refer to evaporative emission purge solenoid trouble code DTC P0446.
STEP 4. Pressure test for evaporator line from hose I to hose P.
1. Disconnect hose F from the evaporative emission canister side, and plug the hose from which the pipes have been disconnected.
2. Perform the pressure test again.
Q: Are there any leaks in the evaporator line?
YES: Go to Step 5.
NO: Go to Step 8.
STEP 5. Check for leaks in the evaporator line hose C to hose E.
1. The leakage test with a hand vacuum pump on each hose from hose C to hose E.
Q: Can the leaks be pinpointed?
YES: Replace the hose. Then go to Step 1.
NO: Go to Step 6.
STEP 6. Check for leaks in the evaporator line from hose F to hose H.
1. Remove the fuel tank.
2. The leakage test with a hand vacuum pump on each hose from hose F to hose H.
Q: Can the leaks be pinpointed?
YES: Replace that hose, reinstall the filler tank. Then go to Step 1.
NO: Go to Step 9.
STEP 7. 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.
Q: Does the vacuum reading fluctuate?
YES: Replace the evaporative emission canister, reinstall the fuel tank. Then go to Step 1.
NO: Go to Step 1.
STEP 8. Check for leaks in the evaporator line hose I, L, M and O.
1. Remove the fuel tank filler neck assembly.
2. The leakage test with a hand vacuum pump on each hose from hose I, L,M,N and O.
Q: Can the leaks be pinpointed?
YES: Replace the hose, reinstall the fuel tank filler neck assembly. Then go to Step 1.
NO: Go to Step 9.
STEP 9. Check the check valve A.
1. Only when you blow the check valve from the direction shown, it should pass air.
2. When you blow the check valve, on air should leak from the check valve body.
Q: Is there any failure?
YES: Replace it, reinstall the filler neck assembly. Then go to Step 1.
NO: Go to Step 10.
STEP 10. Check the check valve B.
1. When you blow the check valve from the arrow direction shown above, it should pass more air.
2. When you blow the check valve from the arrow direction shown below, it should pass less air.
3. When you blow the check valve, on air should leak from the check valve body.
Q: Is there any failure?
YES: Replace it, reinstall the filler neck assembly and filler neck protector. Then go to Step 1.
NO:. Go to step 11.
STEP 11. Check for leaks in the evaporator line from hose J to hose K.
1. Disconnect hose J at the liquid separator, and then connect a hand vacuum pump to the hose.
2. Disconnect hose K at the fuel tank side, and then plug the hose.
3. Apply vacuum by using the hand vacuum pump.
Q: Is the pressure maintained in the evaporator line?
YES: Go to Step 12.
NO: Go to Step l5.
STEP 12. Check for leaks in the evaporator line from hose P.
1. Remove the fuel tank.
2. The leakage test with a hand vacuum pump on each hose from hose P.
Q: Can the leaks be pinpointed?
YES: Replace the hose, reinstall the fuel tank. Then go to Step 1.
NO: Go to Step 13.
STEP 13. 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.
Q: Can the leaks be pinpointed?
There is leaks at the fuel pump assembly or the inner pressure sensor installation section: Reassemble the parts, check again that there are no leaks, reinstall the fuel tank. Then go to Step 1.
There is leaks at another section: Go to Step 14.
STEP 14. Visually check for cracks in the fuel tank filler neck.
1. Visually check for cracks in the fuel tank filler neck.
Q: Can the cracks be found out?
YES: Replace the fuel tank filler neck, reinstall the fuel tank. Then go to Step 1.
NO: Reinstall the fuel tank. Then go to Step 1.
STEP 15. Check for leaks in the evaporator line from hose J to hose K.
1. The leakage test with a hand vacuum pump on each hose from hose J to hose K.
Q: Can the leaks be pinpointed?
YES: Replace the hose, reinstall the fuel tank. Then go to Step 1.
NO: Go to Step 1.