DTC Descriptor
DTC P0455: Evaporative Emission (EVAP) System Large Leak
Diagnostic Fault Information
Always perform the
Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit/System Description
The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module
commands the EVAP canister purge solenoid valve OPEN and the EVAP vent solenoid valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed,
sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent solenoid
valves.
Control Module Command
| EVAP Canister Purge Solenoid Valve
| EVAP Canister Vent Solenoid Valve
|
ON
| Open
| Not Venting
|
OFF
| Closed
| Venting
|
Conditions for Running the DTC
| • | DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0452, P0453, P0502, P0601, P0602, P0606, P0641 are not set. |
| • | The ignition voltage is between 11-18 volts. |
| • | The barometric pressure (BARO) is more than 74 kPa. |
| • | The fuel level is between 15-85 percent. |
| • | The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F). |
| • | The start-up intake air temperature (IAT) is between 4-30°C (39-86°F). |
| • | The start-up ECT and IAT are within 8°C (14.4°F) of each other. |
| • | DTC P0455 runs once per cold start within 10 minutes of start-up. |
Conditions for Setting the DTC
The EVAP system is not able to achieve or maintain vacuum for up to 4 times during the diagnostic test.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp
(MIL) on the second consecutive ignition cycle that the diagnostic runs and
fails. |
| • | The control module records the operating conditions at the time
the diagnostic fails. The first time the diagnostic fails, the control module
stores this information in the Failure Records. If the diagnostic reports
a failure on the second consecutive ignition cycle, the control module
records the operating conditions at the time of the failure. The control
module writes the operating conditions to the Freeze Frame and updates
the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL)
after 3 consecutive ignition cycles that the diagnostic runs and does
not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs
and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles,
if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | A loose, missing, incorrect, or damaged fuel fill cap may cause this DTC to set. |
| • | To help locate intermittent leaks, use the
J 41413-200 to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the
J 41413-SPT High Intensity
White Light . Introducing smoke in 15-second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner. |
| • | To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the
J 41413-SPT . |
| • | Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Special Tools Required
| • | J 41413-200 Evaporative Emission System Tester (EEST) |
Circuit/System Testing
Important:
| • | Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize. |
| • | Refer to the
J 41413-200 operation manual for detailed instructions. |
- Using the
GE-41415-50 , connect the
J 41413-200 to the vehicle filler neck.
- Use the flow meter on the
J 41413-200 , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.
| ⇒ | If a leak is detected use the
J 41413-200 to apply smoke to the EVAP system at the service port or the filler neck until the leak is located. |
- Start the engine with the
J 41413-200 connected to the fuel filler neck.
- Allow the engine to idle.
- Use the Purge/Seal function to seal the system with a scan tool.
- Command the EVAP canister purge solenoid valve to 20 percent.
- The vacuum/pressure gage on the
J 41413-200 and the FTP parameter on the scan tool should both show vacuum.
| ⇒ | If the vacuum/pressure gage on the
J 41413-200 does not show vacuum, check for a restricted purge path. |
- Vacuum should increase on the gage of the
J 41413-200 and scan tool until it reaches approximately 16 inches H2O, or until the vacuum reaches the abort limit on the scan tool.
| ⇒ | If the difference between the FTP parameter on a scan tool and the vacuum/pressure gage on the
J 41413-200 was more than 1 inch, replace the FTP sensor. |
| ⇒ | If the maximum
Fuel Tank Pressure Sensor parameter on a scan tool display was less than 3.2 volts, replace the FTP sensor. |
Repair Instructions
Important: Always perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
