P0455
DTC P0455 EVAP. EMISSION SYSTEM-LEAK DETECTED(LARGE LEAK)GENERAL DESCRIPTION
This test determines the presence of a large leak, such as a fuel fill cap not installed or a hose disconnected, by initially bringing the evaporative system to a vacuum level of 10.2 in H2O during idle conditions. This is done by commanding the vent valve to close and requesting the Canister Purge Subsystem to enter the tank draw mode. NOTE: this vacuum increase process is a continuation of the preset mode process that was initiated during the Preset Large Leak Function. During this vacuum level increase process, the vacuum level in the fuel tank is monitored using a fuel tank pressure sensor for a duration that is determined by the accumulated purge volume that has exited the evaporative system. This accumulated purge volume is determined by the vacuum index tracking logic. A normally functioning or passing evaporative system will achieve the calibration-specified vacuum level before the accumulated purge volume exceeds calibrated threshold, but a failing evaporative system will not achieve this calibration-specified vacuum level.
DTC DESCRIPTION
This test detects a large leak (> 0.04" ) in the evaporative system by measuring the time it takes to draw a pre-determined amount of vacuum in the evaporative system. The inability to draw a vacuum under controlled conditions is indicative of having a large leak. Test failures can be caused by either hardware failures (i.e. a hole, broken seal, etc) or by the customer not correctly reinstalling the gas cap following re-fueling.
The Large Leak test is split up in to two sub-tests, the Preset Large Leak Test and the Idle Large Leak Test. The Idle Large Leak test runs when the vehicle is at idle. The Preset Large Leak test runs when the vehicle is off idle and will report it's results if the diagnostic times out and ends before the vehicle returns to idle.
Checking tank vacuum from tank pressure sensor under detecting condition, if tank vacuum signals is less than 10.0996 at idle condition or not after purge volume has been drawn from tank, PCM sets P0455. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till 1 driving cycle.
DTC Detecting Condition:
MONITOR SCANTOOL DATA
1. Warm-up engine to normal operating temperature-
NOTE: Evaporative Emissions Systems (EVAP) Leak Tests can be run by the Scan Tool The tests are automated and provide either a pass-fail result or directions to check for DTCs.
2. Install scan tool and clear DTC
3. Perform "EVAP. LEAKAGE TEST" mode referring to enable conditions as below
Monitoring for (pending) DTC by performing "DIAGNOSTIC TROUBLE CODES" or "MONITORING TEST RESULTS".Is the same DTC set?
YES: Go to "System Inspection" procedure.
NO: Fault is intermittent caused by poor contact in sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection,bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of vehicle Repair" procedure.
SYSTEM INSPECTION
1. Check vapor hoses for leakage in fuel system.
1. Check vapor hoses between the following components for leakage:
- Intake manifold Purge control solenoid valve (PCSV)
- Purge control solenoid valve (PCSV) - Canister
- Canister - Canister close valve (CCV)
- Canister - fuel tank
2. Does a leak exist?
YES: Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check fuel filler pipe for leakage" as below.
2. Check fuel filler pipe for crack or leakage.
1. Check that there is crack or leakage in fuel filler pipe
2. Is there any crack or leakage?
YES: Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
NO: Go to "Component inspection" procedure.
COMPONENT INSPECTION
1. Check CCV for leakage.
1. Disconnect the hose leading from the CCV to Canister at CCV.
2. Visually Check any tear of the hose leading from the CCV to Canister
3. When the CCV operates, apply a vacuum at the nipple and verify that the CCV holds vacuum.
4. Does a leak exist?
YES: Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check Canister for leakage" as necessary.
2. Check Canister for leakage.
1. Disconnect the hose leading from the CCV to Canister at Canister.
2. When the other nipples are plugged, apply a vacuum at the vent nipple and verify that the Canister holds vacuum
3. Does a leak exist?
YES: Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check fuel tank for leakage" as below.
3. Check fuel tank for leakage.
1. Check fuel tank for crack or leakage.
2. Does a leak exist?
YES: Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO: Substitute with a known - good PCM and check for proper operation.
If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
NOTE: There is a memory reset function on Scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTC.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all readiness tests have been verified as" Complete"
5. Are any DTCs present?
YES: Go to the applicable trouble shooting procedure.
NO: System is performing to specification at this time.