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 if the vacuum level decreases too rapidly, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the Venting or Not Venting 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 |
This diagnostic procedure supports the following DTC:
DTC P0455 Evaporative Emission (EVAP) System Large Leak Diagnostic
• | DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0442, P0443, P0446, P0449, P0452, P0453, P0454, P0455, P0502, P1106, P1107, P1111, P1112, P1114, P1115, P1125, P1516, P2101, P2108, P2119, P2120, P2125, P2135, P2138 are not set. |
• | The ignition voltage is between 10-18 volts. |
• | The barometric pressure (BARO) is more than 75 kPa. |
• | The fuel level is between 15-85 percent. |
• | The engine coolant temperature (ECT) is between 4-30°C (39-86°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 129 km/h (80 mph). |
• | DTC P0455 runs once per cold start when the above conditions are met. |
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 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. |
• | 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. 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. |
• | 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 Testing for Intermittent Conditions and Poor Connections . |
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
2 |
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 3 | ||||||||||
3 |
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 16 | Go to Step 4 | ||||||||||
4 |
Did you locate and repair a leak source? | -- | Go to Step 16 | Go to Step 5 | ||||||||||
5 |
Is the difference between the 2 gages less than the specified value? | 1 in H2O | Go to Step 6 | Go to Step 13 | ||||||||||
Is the fuel tank pressure sensor parameter more than the second specified value? | 10 in H2O 5 in H2O | Go to Step 7 | Go to Step 13 | |||||||||||
7 |
Is the fuel tank pressure sensor parameter less than the specified value? | 1 in H2O | Go to Diagnostic Aids | Go to Step 8 | ||||||||||
8 | Disconnect the EVAP purge pipe from the EVAP canister purge solenoid valve. Is the fuel tank pressure sensor parameter less than the specified value within 90 seconds? | 1 in H2O | Go to Step 14 | Go to Step 9 | ||||||||||
9 | 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 12 | Go to Step 10 | ||||||||||
10 | 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 15 | Go to Step 11 | ||||||||||
11 | Repair the pinched or obstructed EVAP vapor pipe. Did you complete the repair? | -- | Go to Step 16 | -- | ||||||||||
12 | Repair the restriction in the EVAP purge pipe. Did you complete the repair? | -- | Go to Step 16 | -- | ||||||||||
13 | Replace the fuel tank pressure (FTP) sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||||
14 | Replace the EVAP canister purge solenoid valve. Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||||
15 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||||||
16 |
Important: DO NOT exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
Does the J 41413-200 pressure/vacuum gage remain constant? | 5 in H2O | Go to Step 17 | Go to Step 3 | ||||||||||
17 | Compare the fuel tank pressure sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage. Is the difference between the 2 gages less than the specified value? | 1 in H2O | Go to Step 18 | Go to Step 5 | ||||||||||
18 |
Does the pressure decrease? | -- | Go to Step 19 | Go to Step 8 | ||||||||||
19 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |