P0442
TECHNICAL DESCRIPTION- The PCM turns on the evaporative emission ventilation solenoid which shuts off the evaporative emission canister outlet port. Then the evaporative emission purge solenoid is driven. As a result, the fuel system will be set into a negative pressure.
When the fuel system reaches negative pressure, the evaporative emission purge solenoid is turned "off," and the fuel system are sealed. As the fuel pressure inside the fuel tank changes, the PCM judges if there is a leak in the fuel system.
DTC SET CONDITIONS
Check Area
- Engine coolant temperature when the engine starting is lower than 30° C (86° F)
- Intake air temperature is lower than 30° C (86° F) at engine start.
- At least sixteen minutes have passed since the starting sequence was completed.
- Engine coolant temperature higher than 60° C (140° F).
- Engine speed is higher than 1,600 r/min.
- Power steering pressure switch: "OFF"
- Barometric pressure is higher than 76 kPa (11 psi).
- Volumetric efficiency is at between 25 and 80 percent.
- Intake air temperature is higher than 5° C (41° F).
- The pressure rise when the evaporative emission purge solenoid and evaporative emission ventilation solenoid are closed is less than 451 Pa (0.065 psi).
- The pressure fluctuation width is less than 647 Pa (0.094 psi).
- At least twenty seconds have passed since pressure fluctuation detection commenced.
- Fuel tank differential pressure sensor output voltage is 1 - 4 volts.
- Vehicle speed is 30 kph (18.7 mph) or more.
- Monitoring time: 75 - 125 seconds
Judgment Criteria
- Internal pressure of the fuel tank has changed more than 843 Pa (0.122 psi) in 20 seconds after the tank and vapor line were closed.
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.
- Evaporative emission canister is clogged.
- Fuel vent valve failed.
- Purge line or vapor line is clogged.
- Fuel tank, purge line or vapor line seal failed.
- Evaporative emission purge solenoid failed.
- Evaporative emission ventilation solenoid failed.
- Fuel tank differential pressure sensor failed.
- Engine coolant temperature sensor failed.
- Intake air temperature sensor failed.
- Power steering pressure switch failed.
- Use of incorrect fuel.
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.
WIRING DIAGRAM
CONNECTORS
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION : To prevent damage to scan tool MB991502, turn the ignition switch off before connecting 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. Check for other DTCs.
If any other DTCs are set, please check those DTCs first then follow the steps below.
STEP 2. Evaporative Emission System Leak Monitor Test using scan tool MB991502.
NOTE: This monitor is carried out at an engine speed of 1,600 r/min or more, transaxle is in "N" or "R" position. The engine speed has to be automatically adjusted.
1. Erase the DTCs using scan tool MB991502. Ensure that the fuel cap is securely tightened.
2. Select "System Test" and press "YES" key.
3. Select "Evap Leak Mon" and press "YES" key.
4. If "Evap Leak Mon" is selected before starting the engine, "Engine must be running." is displayed. In this case, start the engine and then select "Evap Leak Mon" again.
5. If "Keep the TPS in idle position. during the test." is displayed, the PCM or PCM adjusts engine speed automatically. A manual adjustment for engine speed is not needed.
6. Keep the idling position during the monitor.
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 for the adjustment procedure.
7. Item "In Progress" is displayed during the monitor. Keep the engine speed and load within the defined range. Scan tool MB991502 shows these items on the screen.
Item "In Progress" will be change from "NO" to "YES" by keeping engine conditions.
8. Message "Evap Leak Mon. Completed. Test Passed." is displayed when the test has been completed without malfunction. Evaporative emission system is working property at this time. Please explain to customer that improperly tightened fuel cap can cause to MIL turn on. No further steps are needed.
9. Message "Evap Leak Mon. Completed. Test Failed & DTCs Set." is displayed when a malfunction has been detected during the test. Go to Step 3.
10. Message "Evap Leak Mon. discontinued. Retest again from the first" is displayed when the monitor was discontinued by a certain reason (input vehicle speed, engine speed and engine load was put of the specified range). Turn the ignition switch off once and start monitoring from the beginning.
NOTE: Monitoring will not start unless turning off the ignition switch is turned off once and the engine restarted.
STEP 3. Using scan tool MB991502, check "Fuel tank differential pressure sensor (date list 73)" output.
In this step, the fuel tank differential pressure sensor reading is checked to determine if the fuel tank differential pressure sensor output is within the normal range.
1. Check the MFI data list item: TANK PRS SNSR 73
2. Watch the sensor reading. This value varies depending on pressure inside the fuel tank.
3. Remove the fuel cap.
NOTE: If the fuel cap is not securely tightened, it might have the cause of a leak in the EVAP system and set the DTC P0442.
4. After the fuel cap has been removed, the pressure sensor reading should be between -0.5 kPa (-0.07 psi) and 0.5 kPa (0.07 psi).
- If the reading is between -0.5 kPa (-0.07 psi) and 0.5 kPa (0.07 psi), the fuel tank differential pressure sensor circuit is OK. Therefore, go to Step 4.
- If the reading is not between -0.5 kPa (-0.07 psi) and 0.5 kPa (0.07 psi), the fuel tank differential pressure sensor is not working properly. Replace the fuel tank differential pressure sensor.
STEP 4. Check the fuel vent plunger and flapper door operation.
NOTE: When a fuel nozzle is inserted to the fuel tank filler tube and the flapper door is opened, the fuel vent valve is closed (plunger moves towards the top of the neck). When the fuel cap is closed, the fuel cap pushes the plunger back in, which then opens the vent valve. If the flapper door or plunger does not operate properly the vent valve stays closed even after the fuel cap is closed. This may block the vapor passage. A faulty vent valve plunger may also cause the fuel cap not to seat properly Either of these conditions can set DTC P0442.
1. Remove the fuel cap.
2. Push the flapper in to operate the valve.
NOTE: When the flapper is pushed in, the plunger of the valve should move towards the top.
3. Reinstall and tighten the fuel cap until three clicks are heard.
4. Remove the cap again and check the protrusion of the plunger to verify if it is pushed back.
5. Distance between the tip of vent valve plunger and that of fuel tank filler tube should be 28 mm (1.1 inches) or more.
- If the plunger does not return, replace the fuel tank filler tube and securely tighten the cap.
- If the operation is OK, install and securely tighten the fuel cap.
STEP 5. Using scan tool MB991502, actuator test item 08 : Evaporative Emission Purge Solenoid.
1. Disconnect the hose connected to the evaporative emission canister from the purge solenoid.
2. Connect a hand vacuum pump to the nipple where the hose is disconnected at the previous step.
3. The vacuum should be maintained when vacuum is applied and vacuum should leak when the purge solenoid is activated by the actuator test of scan tool MB991502.
- If correct, go to Step 6.
- If not,Refer to DTC P0443 (Evaporative Emission Control System Purge Control Valve Circuit Malfunction).
STEP 6. Using scan tool MB991502, actuator test item 29 evaporative Emission Ventilation Solenoid.
1. Disconnect the hose connected to the vent solenoid valve from the evaporative emission canister.
2. Connect a hand vacuum pump to the hose that is disconnected in the previous step.
3. The vacuum should leak when vacuum is applied, and the vacuum should be maintained when the purge solenoid is activated by the actuator test of scan tool MB991502.
- If correct, go to Step 7.
- If not, refer to DTC P0446 (Evaporative Emission Control System Vent Control Malfunction).
STEP 7. Performance test.
NOTE: Fuel temperature should be lower than 40° C (104° F) during the performance test
In this step, verify if the EVAP system works properly, or determine which area of the evaporative emission system has a failure.
CAUTION : As a 0 - 6.2 kPa (C-0.90 psi) range vacuum gauge is used, the gauge may be broken if excessive vacuum pressure is applied. Do not apply a vacuum of more than 2-9 kPa (0.42 psi).
To achieve the performance test efficiently, a mechanical vacuum gauge [0 - 6.2 kPa (0 - 0.90 psi) range] and scan tool MB991502 should be used, and the engine to generate vacuum.
1. Install a mechanical vacuum gauge [0 - 6.2 kPa (0 - 0.90 psi) range] between the EVAP purge solenoid valve and the purge hose that comes from the evaporative emission canister.
2. Before starting the performance test, set the vehicle in the following condition.
- Engine coolant temperature: 80 - 90 ° C (176 - 203 ° F)
- Lights and all accessories: OFF
- Transaxle: "N" or "P" position
3. Select the item TANK PRS SNSR (data list 73) on scan tool MB991502 to see the differential pressure sensor output.
4. Run the engine at idle.
5. Using locking pliers, pinch the hose between the purge solenoid and the intake plenum to close the purge flow, as a preparation of the performance test.
6. Using another locking pliers, pinch the vent hose between the evaporative emission canister and the vent solenoid. Momentary, remove the locking pliers at the purge hose; this will cause the vacuum build up in the EVAP system.
7. The engine vacuum comes from the purge port through the purge solenoid.
NOTE: During This operation, the purge solenoid may turn off but will resume operation in about 20 seconds. Operation of the purge solenoid can be checked by needle fluctuation of the mechanical vacuum gauge.
8. Watch the vacuum reading on the mechanical vacuum gauge and scan tool MB991502.
9. When the vacuum reading reaches 2.9 kPa (0.42 psi) on the mechanical vacuum gauge and -2.9 kPa (-0.42 psi) on scan tool MB991502, pinch the hose between the purge solenoid and the intake manifold plenum using another locking pliers; this stops the application of vacuum and seals the EVAP system for the leak test.
NOTE: If there is a system failure, either of both vacuum readings may not reach to the above specifications. In this case, it is not necessary to pinch off the purge hose as shown. Refer to the performance test results table for further steps.
10. After an elapsed time of 20 seconds, check the fuel tank differential pressure reading on scan tool MB991502.
OK: Change in pressure reading is 0.4 kPa (0.06 psi) or less [holding -2.5 kPa (-0.36 psi) or more vacuum].
Performance test result table:
STEP 8. Vacuum reading on both the mechanical gauge and scan tool MB991502 reaches the specifications and satisfy the specifications after 20 seconds
EVAP system is properly working at the moment. The cause of DTC might have been a loose fuel cap and the customer may have already tightened fuel cap causing the MIL to turn on. No further steps are needed.
STEP 9. Vacuum reading on the mechanical gauge reaches 2.9 kPa (0.42 psi) but scan tool MB991502 does not reach -2.9 kPa (-0.42 psi)
1. If the vacuum reading on the gauge reaches 2.9 kPa (0.42 psi) but the reading on scan tool MB991502 does not reach -2.9 kPa (-0.42 psi), either a system blockage or a bad differential pressure sensor may be the cause.
2. To determine if there is a blockage in the system, remove the fuel cap.
- If the vacuum reading on the vacuum gauge [at this point 2.9 kPa (0.42 psi)] remains the same, there is a blockage in the system. Go to Step 10.
- If the reading drops to about 0 kPa (0 psi), there is no blockage in the EVAP system. The fuel tank differential pressure sensor needs to be replaced. After replacing the differential pressure sensor, go to Step 13.
STEP 10. System blockage inspection.
1. Disconnect the number 1 and 2 hoses shown in the illustration, check the mechanical vacuum gauge reading.
If the vacuum reading does not drop, then the blockage is not in the fuel tank.
2. Disconnect one portion of the EVAP system at a time working towards the front of the vehicle until blockage is found (number 1 to 5 hoses in the illustration).
3. Repair the location of the blockage and go to Step 13.
STEP 11. Vacuum readings on both the mechanical gauge and scan tool MB991502 do not reach the specifications [2.9 kPa (0.42 psi) and -2.9 kPa (-0.42 psi)]:
This condition shows that there is a significant leakage in the system. The inspection procedure for the large system leakage is the same as the small leakage test in Step 12.
STEP 12. Vacuum readings on both the mechanical gauge and scan tool MB991502 do not reach the specification [2.9 kPa (0.42 psi) and -2.9 kPa (-0.42 psi)] but do not maintain the vacuum.
This condition shows that there is a slight leakage in the system. Follow the procedure below to locate the source of the leak.
1. The fuel cap relief valve inspection.
a. Remove the fuel cap and install the fuel tank filler tube adapter in the emission system tester kit in place of the fuel cap.
b. Plug the nipple on the fuel tank filler tube adapter.
c. Replace the performance test. If the EVAP system holds the vacuum, then the fuel cap is faulty. Replace the fuel cap, and go to Step 13.
2. To find the vacuum leakage in the system, clamp the number 1 and 2 hoses shown in the illustration. Repeat the performance test. This will determine if the vacuum leak is either in the fuel tank area or in the rest of the system.
NOTE: In this case, as we clamped off the vacuum hose connecting to the fuel tank, scan tool MB991502 reading will not change. Please use the mechanical gauge reading.
- If the EVAP system hold the vacuum leak is in the fuel tank area. To locate the leakage, pressurize the EVAP system to 3.4 kPa (0.49 psi) and look for leaky area using the ultrasonic leak detector in the Evaporative Emission System Tester. After repairing the leakage, go to Step 13.
- If the vacuum leak still exists, the leak is at other than fuel tank area.
3. Clamp off the vacuum hose one component at a time working towards the front of the vehicle until leakage is found (number 1 to 5 hoses shown in the illustration).
4. Repair the leakage at that location and go to Step 13.
STEP 13. Confirmation test.
After system failures are repaired, repeat the Evaporative Emission System Leak Monitor test (Step 2) to check that the EVAP system operates correctly.