Advanced Diagnostics

DTC P0497: Evaporative Emission (EVAP) System Low Purge Flow




General Description
There are two conditions when the evaporative emission (EVAP) system will not hold vacuum, and the pressure in the fuel tank doesn't become negative.

1. EVAP system low purge flow.
2. EVAP system leakage or the fuel fill cap is loose/off.

Here is a description of condition 1:

The malfunction detection is done during EVAP system leak detection (P0455, P0456).

The engine control module (ECM)/powertrain control module (PCM) monitors the fuel tank pressure (FTP) sensor output. If the FTP sensor output does not indicate the prescribed negative pressure when purging, the ECM/PCM detects a malfunction 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 at least -0.2 kPa (-0.07 in.Hg, -2 mmHg) for up to 45 seconds.

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

Driving Pattern
1. After the vehicle has been left for an appropriate amount of time as specified, with the engine coolant temperature and intake air temperature within the specified range, start the engine.
2. Warm up the engine at idle until the radiator fan comes on.
3. Drive the vehicle immediately at a speed between 45 - 75 mph (72 - 120 km/h) for at least 20 minutes.
4. After stopping the engine, turn the ignition switch off, and leave the vehicle for 32 minutes or more (EONV executes).

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL
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 Temporary DTC is stored in the ECM/PCM memory. If the malfunction recurs during the next (second) drive cycle with the ECT and IAT at engine start-up within the specified temperature range, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.