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 canister 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. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and solenoid vent valves.
Control Module Command | EVAP Canister Purge Solenoid Valve | EVAP Canister Vent Solenoid Valve |
---|---|---|
ON | Open | Closed |
OFF | Closed | Open |
This diagnostic procedure supports the following DTC:
DTC P0455 Evaporative Emission (EVAP) System Large Leak
• | DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125 if applicable, P0443, P0446, P0449, P0452, P0453, P0496, P0502, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122 are not set. |
• | The engine is running. |
• | The ignition voltage is between 10-18 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 less than 30°C (86°F). |
• | The intake air temperature (IAT) is between 4-30°C (39-86°F). |
• | The start-up ECT and IAT are within 9°C (16°F) of each other. |
• | The vehicle speed sensor (VSS) is less than 121 km/h (75 mph). |
The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.
• | 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. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after the first time 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. |
• | To help locate intermittent leaks, use the J 41413-200 Evaporative Emission System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. |
• | A temporary blockage in the EVAP canister purge solenoid valve, purge pipe, or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system. |
• | 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. |
• | For intermittent conditions, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
This step verifies that a failure condition is active.
Introducing smoke in 15-second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
This step verifies proper operation of the FTP sensor.
A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6-7 inches of H2O.
This step tests the EVAP canister purge solenoid valve vacuum source between the EVAP canister purge solenoid valve and the intake manifold for restrictions or blockages.
Step | Action | Values | Yes | No | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||||
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 3 | |||||||||||
3 |
Important: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
Is the floating indicator below the red flag? | -- | Go to Step 6 | Go to Step 4 | ||||||||||
Important: Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. System flow will be less with higher temperatures.
Did you locate and repair a leak source? | -- | Go to Step 23 | Go to Step 5 | |||||||||||
5 |
Did you locate and repair a leak source? | -- | Go to Step 23 | Go to Step 6 | ||||||||||
Is the difference between the 2 gages less than the specified value? | 1 in H2O | Go to Step 7 | Go to Step 15 | |||||||||||
Is the Fuel Tank Pressure Sensor parameter more than the second specified value? | 10 in H2O 5 in H2O | Go to Step 8 | Go to Step 15 | |||||||||||
8 |
Is the Fuel Tank Pressure sensor parameter less than the specified value? | 1 in H2O | Go to Step 9 | Go to Step 11 | ||||||||||
Is the FTP parameter on a scan tool within the specified value of the vacuum/pressure gage on the J 41413-200 until the vacuum reached the abort limit on a scan tool? | 1 in H2O | Go to Step 10 | Go to Step 15 | |||||||||||
10 | Did the FTP parameter on a scan tool display more than the specified value? | 3.2 V | Go to Diagnostic Aids | Go to Step 20 | ||||||||||
11 | Disconnect the EVAP purge vacuum source from the EVAP canister purge solenoid valve. Is the Fuel Tank Pressure sensor parameter less than the specified value? | 1 in H2O | Go to Step 17 | Go to Step 12 | ||||||||||
12 | Disconnect the EVAP purge pipe from the EVAP canister purge solenoid valve. Is the Fuel Tank Pressure sensor parameter less than the specified value? | 1 in H2O | Go to Step 17 | Go to Step 13 | ||||||||||
13 | Disconnect the EVAP purge pipe at the EVAP canister. Is the Fuel Tank Pressure sensor parameter less than the specified value? | 1 in H2O | Go to Step 19 | Go to Step 14 | ||||||||||
14 | Disconnect the EVAP vapor pipe at the EVAP canister. Is the Fuel Tank Pressure sensor parameter less than the specified value? | 1 in H2O | Go to Step 22 | Go to Step 18 | ||||||||||
15 | Test for an intermittent and for a poor connection at the fuel tank pressure (FTP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 16 | ||||||||||
16 | Test the low reference circuit of the FTP sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 20 | ||||||||||
17 | Repair the pinched or obstructed EVAP purge solenoid valve vacuum source. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||||
18 | Repair the pinched or obstructed EVAP vapor pipe. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||||
19 | Repair the restriction in the EVAP purge pipe. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||||
20 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||
21 | Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||
22 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||
23 | Perform the Service Bay Test. Refer to Service Bay Test . Does the scan tool indicate that the Service Bay Test passed? | -- | Go to Step 24 | Go to Step 3 | ||||||||||
24 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |