| Table 1: | P0496 Evaporative Emission (EVAP) System Flow During Non-Purge |
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 valve Closed and the EVAP canister vent 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 valves.
Control Module Command | EVAP Canister Purge Valve | EVAP Canister Vent Valve |
|---|---|---|
ON | Open | Closed |
OFF | Closed | Open |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0496 Evaporative Emission (EVAP) System Flow During Non-Purge
Conditions for Running the DTC
| • | Before the engine control module (ECM) can report DTC P0496 failed, DTC P0451 must run and pass. |
| • | DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0221, P0222, P0223, P0443, P0446, P0449, P0451, P0452, P0453, P0458, P0459, P0451, P0452, P0453, P0498, P0499, P0560, P0562, P0563, P0722, P0723, P2122, P2123, P2127, P2128, and P2138 are not set. |
| • | The fuel system is in closed loop. |
| • | The vehicle speed sensor (VSS) is less than 3 km/h (2 mph). |
| • | The engine is idling. |
| • | The ignition 1 voltage is between 10.5-18 volts. |
| • | The FTP is between -2.5 and +1.0 kPa. |
| • | The ratio between the ambient pressure and the calculated manifold pressure is less than 0.55. |
| • | The start-up engine coolant temperature (ECT) is between 4-65°C (39-149°F). |
| • | The start-up intake air temperature (IAT) is between 4-30°C (39-86°F). |
| • | The fuel tank level is between 15-85 percent. |
| • | The barometric pressure (BARO) is more than 68 kPa. |
| • | DTC P0496 runs once an ignition cycle. The ECM will attempt to run this diagnostic up to 10 times an ignition cycle. |
Conditions for Setting the DTC
The control module detects vacuum during a non-purge condition.
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 4 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
| • | Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | 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 valve. For an intermittent condition, refer to Intermittent Conditions |
Test Description
The number below refers to the step number on the diagnostic table.
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 | Are DTCs P0443, P0451, P0452, or P0453 also set? | -- | Go to Step 3 | |
Does the scan tool indicate FTP within the specified range? | -1.0 to +1.0 in H2O | Go to Step 4 | Go to DTC P0451 | |
4 |
Does the gage indicate an increase in vacuum? | -- | Go to Step 5 | Go to Diagnostic Aids |
5 | Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 6 | -- |
6 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Step 7 |
7 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
