DTC P0441, P0442

Evaporative Emission Control System Incorrect Purge Flow Evaporative Emission Control System Leak Detected (Small)

System Diagram













TECHNICAL DESCRIPTION
•To judge if there is leak in the fuel system, the PCM measures 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 a 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.

PO441
Check Conditions
•ON duty cycle of the evaporative emission purge solenoid has been at 0 percent for at least 20 seconds.
Judgement Criteria
•The pressure in the fuel tank is -2kPa (0.29 psi) or less.

PO442
Check Condition
At Start Up
•Engine coolant temperature is lower than36°C (97°F) when engine started.
•Intake air temperature is lower than 36°C (97°F) when engine started.
For Test To Run
•Engine coolant temperature is higher than60°C (140°F).
•Barometric pressure is above 76 kPa (11 psi).
•Volumetric efficiency is between 25 and 80 percent.
•The fuel temperature is 36°C (97°F) or lower.
•Fuel tank differential pressure sensor output voltage is 1 to 4 volts
•Power steering fluid pressure switch is: OFF.
•Vehicle speed is 20km/h (12.4mph) or more
•Intake air temperature is higher than -10°C (14°F).
•The internal pressure change in the fuel tank when the evaporative emission purge solenoid and evaporative emission ventilation solenoid are closed is within 451 Pa (0.065 psi).
•The internal pressure fluctuation width of the fuel tank is less than 647 Pa (0.094 psi).
•Intake manifold pressure is between 27 and 93kPa (3.9 and 13.5psi)
Judgment Criteria
•Internal pressure of the fuel tank has changed more than 647Pa (0.094 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.
•Evaporative emission canister is clogged.
•Fuel overflow limiter valve failed.
•Fuel tank, purge line or vapor line seal failed.
•Purge line or vapor line is clogged.
•Evaporative emission purge solenoid failed.
•Evaporative emission ventilation solenoid failed.
•Fuel tank differential pressure sensor failed.
•Intake air temperature sensor failed.
•Engine coolant temperature sensor 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 "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 PCM automatically increases the engine speed to 1,600 r/min or more. Check that the transmission is set to "N" or "P." (1)Turn the ignition switch to "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 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." (9)The message "Evap Leak Mon. Completed Test Passed" displays when the test has been completed without malfunction. 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. (10)The message "Evap Leak Mon. Completed. Test Failed and DTC's Set" displays when a malfunction has been detected during the monitor test. Go to Step 2. (11)The message "Evap Lead Mon. discontinued. Retest again from the first" is displayed when 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 "LOCK" (OFF) position once, and repeat the monitoring from the start.

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. Pressure test for evaporator line from hose C to hose N. (1)Using locking pliers, pinch hose G between the canister and the evaporative emission ventilation solenoid. (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 the 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 I/M240 Simulation Test (8 simple steps) described in the evaporative emission system pressure pump (Miller number 6872A) manufacturer's instructions located in the lid of the pump box. If no leaks are indicated, go to Step 4. If a leak is indicated, go to Step 5.

STEP 4. Check the evaporative emission ventilation solenoid using the scan tool MB991502. (Actuator test item 29) (1)Lower the evaporative emission canister assembly, turn the ignition switch to "ON" position, and disconnect hose G from the evaporative emission ventilation solenoid side. (2)Connect a hand vacuum pump to the nipple of the evaporative emission ventilation solenoid from which the hose has 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 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 5. Pressure test for evaporator line from hose H to hose L. (1)Using locking pliers, pinch hose F between the canister and purge pipe. (2)Perform the pressure test again. If no leaks are indicated, go to Step 6. If a leak is indicated, go to Step 8.

STEP 6. Check for leaks in the evaporator line from hose C to hose E Perform leakage test with a hand vacuum pump on each hose from hose C to hose E. 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 7.

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. If the vacuum does not fluctuate, go to Step 1. If the applied vacuum fluctuates, replace the evaporative emission canister and go to Step 1.

STEP 8. Check for leaks in the evaporator line hose J and hose K. Perform leakage test with a hand vacuum pump on each hose from hose J and hose K. 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 9.

STEP 9. Check for leaks in the evaporator line from hose L , M and N. (1)Remove the fuel tank. (Refer to GROUP 13F, Fuel Tank) (2)Perform a leakage test with a hand vacuum pump on each hose from hose L M and N. If the location of the leak is pinpointed, replace that hose and install the fuel tank. Then go to Step 1. If the location of the leak cannot be pinpointed, go to Step 10.

STEP 10. 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 return pipe nipple.

(3)Plug the filler hose, fuel cut valve nipple, leveling valve nipple and feed pipe 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 11.

STEP 11. Visually check for cracks in the fuel tank filler neck. Visually check for cracks in the fuel tank filler neck. If cracks are found, replace the fuel filler neck, and install the fuel tank. Then go to Step 1. If any cracks are not found, install the fuel tank. Then go to Step 1.