P0456
DTC P0456 EVAP EMISSION SYSTEM-LEAK DETECTED (VERY SMALL LEAK)Component Location:
COMPONENT LOCATION
GENERAL DESCRIPTION
Due to the increasing ambient temperature of the fuel and the return of unused hot fuel from the engine, fuel vapors are generated in the tank. In order to control the release of these vapors to the atmosphere, the evaporative emissions control system is used. The evaporative emission control system reduces hydrocarbon (HC) emissions by trapping fuel tank vapors until they can be burned in the combustion process. Evaporating fuel is stored in a charcoal canister until it can be flushed into the intake manifold. The evaporative emission control system is made up of a fuel tank that can be completely sealed from outside air, a Fuel Tank Pressure Sensor (FTPS), a Canister Close Valve (CCV) that seals the canister from the outside air, a canister filled with activated charcoal granules, a Purge Control Solenoid Valve (PCSV). The evaporative emission system can be checked for leaks by sealing the system off from the outside air, creating a vacuum, and monitoring if the system can hold that vacuum sufficiently for a set amount of time. If it cannot, a leak exists somewhere in the system.
DTC DESCRIPTION
It there is small leak(0.02 inch) in system, the PCM determines that a fault exists and a DTC is stored.
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 "05 EVAP LEAKAGE TEST" mode referring to enable conditions as above.
4. Monitoring for (pending) DTC by performing "01. DIAGNOSTIC TROUBLE CODES" or "04. 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 ECM 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 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. Does a malfunction exist?
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 PCSV for leakage
1. Disconnect the hose leading from the PCSV to the intake manifold at PCSV.
2. Apply a vacuum at the nipple and verify that the PCSV 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 CCV for leakage" as below.
2. Check CCV for leakage
1. Disconnect the hose leading from the CCV to Canister at CCV.
2. When the CCV is operated, apply a vacuum at the nipple and verify that the CCV 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 Canister for leakage" as necessary.
3. 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.
4. Check fuel tank for leakage
1. Check fuel tank for crack or leakage.
2. Does a teak 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.
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 DTCs.
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 troubleshooting procedure.
NO: System is performing to specification at this time.