For 1990-2009 cars

### 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 P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0442, P0443, P0449, P0452, P0453, P0455, P0502, P0503, P1111, P1112, P1114, P1115, and P1120 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 (15°F) of each other.

• | The vehicle speed sensor (VSS) is less than 121 km/h (75 mph).

• | DTC P0496 runs once per trip.

### Conditions for Setting the DTC

• | A continuous open purge flow condition is detected during the diagnostic test.

• | The FTP decreases to less than -11 inches H2O for up to 65 seconds.

### 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.

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
2 |

1. Start the engine.
2. Seal the evaporative emission (EVAP) system using the Purge/Seal function with a scan tool.
3. Increase the engine idle to 1,200-1,500 RPM.
4. Observe the fuel tank pressure sensor in H2O with a scan tool.

Is the fuel tank pressure sensor parameter within the specified value?

-1 to +1 H2O

Go to Intermittent Conditions

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the EVAP purge pipe from the EVAP purge solenoid solenoid.
3. Turn ON the ignition, with the engine OFF.
4. Observe the fuel tank pressure sensor in H2O with a scan tool.

Is the fuel tank pressure sensor parameter within the specified range?

-1 to +1 H2O

Go to Step 4

Go to Step 5

4 | Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 6 | --
5 | Replace the fuel tank pressure (FTP) sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 6 | --
6 |

1. Connect all EVAP hardware that was previously disconnected.
2. Seal the EVAP system using the Purge/Seal function with a scan tool.
3. Start the engine and idle at 1,200-1,500 RPM.
4. Observe the fuel tank pressure sensor parameter with a scan tool.

Is the fuel tank pressure sensor parameter within the specified range?

-1 to +1 H2O

Go to Step 7

Go to Step 2

7 | 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 | System OK