P0442/P0455 (DTC 160/161)
DTC 160 EVAPORATIVE EMISSION CONTROL SYSTEM SMALL LEAK DETECTED (General Scan Tool Code No. P0442)DTC 160 Diagnosis
It is very important to read and understand the EVAP system information before attempting diagnosis.
Description
Under conditions required for the evaporative emission control system monitor to run, the PCM will set DTC 160 or DTC 161 during the EVAP Leak Detection Test if it detects a leakage. The PCM monitors the LDP cycle rate to determine whether a large or small leak exists.
DTC 160 is set if a leak in the evaporative system between 1 mm (0.040") and 2.0 mm (0.080") exists. DTC 161 is set if a leak in the evaporative system larger than 2 mm (0.080") exists.
IMPORTANT:
Before beginning this procedure, repair all vehicle conditions for DTCs that are not related to the EVAP system. If more than one EVAP system DTC is set, diagnose and repair in the following order:
(1) DTC 183 (P1495)
(2) DTC 184 (P1494)
(3) DTC 187 (P1486)
(4) DTCs 160/161 (P0442/P0455)
! WARNING
The vehicle fuel tank must be 1/2 full of fuel when performing the following test procedure. Pressurizing a fuel tank containing less than three gallons could result in explosion.
NOTE:
The following tools are required for diagnosing DTCs 160 and 161:
^ Two pairs of hose crimping pliers (Snap-On part no. YA965 or equivalent)
^ Evaporative System Pressure Pump Miller Tool No. 6872A (This tool will be shipped to MMSA dealers in September, 1998.)
^ MUT-II scan tool and adapter harness MB991545
^ Continuous vacuum source (A hand-operated vacuum pump may not provide sufficient vacuum)
1. Connect the MUT-II scan tool and adapter harness MB991545. Then turn the ignition key to ON.
2. Enter LDP Hold Mode by following the MUT-II selection sequence below:
3. Apply 15 in/Hg (51 kPa) of continuous vacuum to the system at the SVST. This will move the LDP diaphragm to its upper position and close the vent valve.
NOTE:
A hand-operated vacuum pump may not provide sufficient vacuum for this procedure.
! WARNING
Follow the pump manufacturer's safety precautions. To prevent ignition of explosive gases when using the tester, keep lighted sparks, flames, and other ignition sources away from the test area. Keep the test area well-ventilated.
NOTE:
The EVAP pressure pump (Miller # 6872A) will be shipped to MMSA dealers in September, 1998.
4. Confirm that the EVAP pressure pump (Miller # 6872A) is operating properly. Perform the self-test as described in the manufacturer's instructions.
5. Install the EVAP pressure pump outlet hose to the service port as described in the pump manufacturer's instructions.
6. 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 EVAP pressure pump (Miller # 6872A) manufacturer's instructions located in the lid of the pump box.
a. If no leaks are indicated, perform a visual inspection of the evaporative emission system hoses. Check for any condition that could cause an intermittent leak. Then go to page 39 of this bulletin for the Readiness Test.
NOTE:
DTC 160 or 161 could have been set due to a loose gas cap which was corrected before this diagnosis test was performed. Inform the customer about tightening the gas cap until three clicks are heard.
b. If a leak is indicated, go to Step 7.
7. Tighten the gas cap until you hear three clicks.
8. Pressure test the system again.
a. If no leaks are indicated, go to the Readiness Test of this bulletin.
b. If a leak is indicated, go to Step 9.
9. Remove the gas cap and visually inspect it for damage, wear, or deterioration.
a. If damage, wear, or deterioration is found, replace the gas cap. Then repeat Step 8.
b. If no damage is found, pressure test the gas cap (using gas cap adapter Miller part no.6922 provided with the pump). Be sure to clamp the hose in the middle of Miller part no. 6922 during the pressure test.
(1) If necessary, replace the gas cap. Then repeat Step 8.
(2) If OK, go to Step 10.
10. Inspect the overflow limiter valve (OFLV) plunger for proper alignment with the gas cap. If the plunger interferes with gas cap sealing, this could cause a leak. The plunger should be pushed in by the gas cap as the gas cap is being tightened. (Plunger will not bottom out completely.)
a. If the plunger is not pushed in as the gas cap is being tightened, replace the fuel filler neck. Reinstall the gas cap, then go back to Step 6.
b. If the plunger operates properly (no interference or binding), go to Step 11.
11. Reinstall the gas cap, tightening it until you hear three clicks.
12. Locate the small (approximately three inches long, 1/4" diameter) hose above the rear crossmember. Using hose pinching pliers, pinch off this hose between the floor pipe and the OFLV pipe. Then pressure test the system again.
a. If a leak is still indicated, the leak is forward of the pliers. Leave the pliers clamped on the hose and go to Step 13.
b. If no leak is indicated, the leak is in the rear of the vehicle. Remove the pliers. Go to Step 19.
13. Remove the right front tire and wheel assembly and the splash shield to across the LDP, canister, and associated hoses.
14. On the EVAP pressure pump, set the pressure/hold valve to OPEN, and set the vent valve to CLOSED. Turn the pump timer to ON. You can reset the timer as required. (These settings are listed under "Leak Test" in the pump instructions.)
NOTE:
Location(s) of leakage can be found by using any of the following methods:
^ Ultrasonic leak delector
If using an ultrasonic leak detector move the EVAP pressure pump away from the vehicle to prevent pump noise from interfering with the ultrasonic leak detector.
^ Apply soapy water and check for bubbles
^ Visual inspection (feel for air leaks and smell for fuel vapor)
15. At the canister, pinch off the hose between the service port and the canister.
a. If leak is still indicated, go to Step 16.
b. If no leak is indicated, remove the pliers and go to Step 17.
16. Determine the location of the leakage between the canister and purge solenoid. Inspect hose, purge solenoid, and the service port for signs of leakage. Repair or replace as necessary. Then go the Readiness Test of this bulletin.
17. At the canister, pinch off the hose between the canister and the floor pipe.
a. If a leak is still indicated, do not remove the pliers. At the LDP, remove the hose between the canister and the LDP. Plug the hose using a plug supplied with the EVAP pressure pump.
(1) If a leak is still indicated, go to Step 18.
(2) If no leak is indicated, replace the LDP. Then go the Readiness Test to of this bulletin.
b. If no leak is indicated, remove the pinching pliers. Determine the location of the leakage between the canister and the floor pipe.
18. At the canister, remove the hose between the canister and the LDP. Plug the canister port with a plug supplied with the EVAP pressure pump.
a. If a leak is still indicated, replace the canister. Then go to the Readiness Test of this bulletin.
b. If no leak is indicated, replace the hose between the canister and the LDP. Then go to the Readiness Test of this bulletin for.
19. Inspect for signs of leakage at the hoses and pipes at the fuel filler neck.
a. If a leak is found, replace as required. Then go to the Readiness Test of this bulletin.
b. If no leak is found, go to Step 20.
20. Remove the rear seat cushion and the two inspection covers. Inspect for signs of leakage around the fuel pump and the fuel gauge unit.
a. If a leak is found, replace as required. Then go to the Readiness Test of this bulletin.
b. If no leak is found, go to Step 21.
21. Be sure the EVAP pressure pump is turned off. Remove the fuel tank as described in Group 13 of the appropriate service manual.
22. Inspect the fuel tank, rollover valve, and associated lines and hoses for signs of leakage. Replace as required. Then go to the Readiness Test of this bulletin.