Advanced Diagnostics

Advanced Diagnostics - DTC P0496: Evaporative Emission (EVAP) System High Purge Flow






General Description
The powertrain control module (PCM) adjusts the amount of fuel vapor sent to the engine by controlling the evaporative emission (EVAP) canister purge valve. If the EVAP canister purge valve is stuck open, engine vacuum flows into the purge line before purge control starts when starting the engine. The PCM monitors the fuel tank pressure (FTP) sensor output when purge control starts. If the FTP sensor output indicates negative pressure, the PCM detects a malfunction in the EVAP canister purge valve, and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The output from the fuel tank pressure sensor is -2 kPa (-0.6 inHg, -15 mmHg) or less for at least 10 seconds.

Confirmation Procedure with the HDS
Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.

Driving Pattern
Start the engine under Enable Conditions (see "Initial condition A", "Initial condition B", "Initial engine coolant temperature", and "Initial intake air temperature"), and let it idle until the radiator fan comes on.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle with the ECT and IAT at engine start-up within the specified temperature range, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle with the ECT and IAT at engine start-up within the specified temperature range, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.