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 valve OPEN and the EVAP vent 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 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 vent valves.
Control Module Command | EVAP Canister Purge Valve | EVAP Canister Vent Valve |
---|---|---|
ON | Open | Closed |
OFF | Closed | Open |
• | DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106, P1107, P1112, P1114, P1115, P1121, P1122 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 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 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 Emissions 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 purge solenoid, 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.
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 fuel tank pressure (FTP) sensor.
A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6 inches of H2O and 7 inches of H2O.
Step | Action | Values | Yes | No | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram | ||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||
2 |
Did you find and correct the condition? | -- | Go to Step 21 | 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 21 | Go to Step 5 | |||||||||||
5 |
Did you locate and repair a leak source? | -- | Go to Step 21 | Go to Step 6 | ||||||||||
Is the scan tool Fuel Tank Pressure Sensor parameter within the specified value of the J 41413-200 pressure/vacuum gage? | 1 in H2O | Go to Step 7 | Go to Step 14 | |||||||||||
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 14 | |||||||||||
8 |
Is the Fuel Tank Pressure Sensor parameter Less than the specified value? | 1 in H2O | Go to Step 9 | Go to Step 11 | ||||||||||
9 |
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 14 | ||||||||||
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 18 | ||||||||||
11 | Disconnect the EVAP purge pipe from the EVAP purge solenoid. Is the Fuel Tank Pressure Sensor parameter Less than the specified value? | 1 in H2O | Go to Step 19 | Go to Step 12 | ||||||||||
12 | 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 17 | Go to Step 13 | ||||||||||
13 | 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 20 | Go to Step 16 | ||||||||||
14 | 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 21 | Go to Step 15 | ||||||||||
15 | 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 21 | Go to Step 18 | ||||||||||
16 | Repair the pinched or obstructed EVAP vapor pipe. Did you complete the repair? | -- | Go to Step 21 | -- | ||||||||||
17 | Repair the restriction in the EVAP purge pipe. Did you complete the repair? | -- | Go to Step 21 | -- | ||||||||||
18 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||
19 | Replace the EVAP purge solenoid. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||
20 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||||
21 | Perform the Service Bay Test. Refer to Service Bay Test . Does the scan tool indicate that the Service Bay Test passed? | -- | Go to Step 22 | Go to Step 3 | ||||||||||
22 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |