System Description
This DTC tests for undesired intake manifold vacuum flow to the evaporative emission (EVAP) system. The control module seals the EVAP system by commanding the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Closed. The control module monitors the fuel tank pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is more than a predetermined value within a predetermined time, 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 solenoid valves.
Control Module Command | EVAP Canister Purge Solenoid Valve | EVAP Canister Vent Solenoid Valve |
|---|---|---|
ON | Open | Closed |
OFF | Closed | Open |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0496 Evaporative Emissions (EVAP) System Flow During Non-Purge
Conditions for Running the DTC
| • | DTCs P0068, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0220, P0442, P0446, P0452, P0453, P0455, P0502, P0503, P0601, P0602, P0604, P0606, P060D, P060E, P0641, P1133, P1516, P1621, P2101, P2120, P2125, P2135, P2138, P2176 are not set. |
| • | The ignition voltage is between 11-18 volts. |
| • | The barometric pressure (BARO) is more than 74 kPa. |
| • | The throttle position (TP) is between 7-35 percent. |
| • | 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. |
| • | The vehicle speed sensor (VSS) is less than 137 km/h (85 mph). |
| • | DTC P0496 runs once per trip when the above conditions are met. |
Conditions for Setting the DTC
The control module detects excessive vacuum during a non-purge condition within a 2-minute 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
| • | An intermittent condition could be caused by an improperly installed or damaged EVAP canister purge valve or a temporary blockage in the EVAP canister purge solenoid valve. |
| • | For intermittent conditions, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step inspects for a leaking EVAP canister purge solenoid valve.
-
Removing the fuel fill cap will equalize the pressure inside the tank with atmospheric pressure. At 0 inches of H2O the FTP sensor should be near 1.5 volts. If the sensor is not, there is a concern with the sensor or related wiring.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram and Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the vacuum gage indicate an increase in vacuum? | -- | Go to Step 8 | Go to Step 3 | |
3 |
Does the vacuum gage indicate an increase in vacuum? | -- | Go to Step 5 | Go to Step 4 |
Is the Fuel Tank Pressure Sensor parameter within the specified value? | -0.5 to +0.5 in H2O | Go to Diagnostic Aids | Go to Step 6 | |
5 | Test the control circuit of the EVAP canister purge solenoid valve for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the conditions? | -- | Go to Step 9 | Go to Step 8 |
6 | 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 9 | Go to Step 7 |
7 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
8 | Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 10 |
10 | 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 |
