Advanced Diagnostics
Advanced Diagnostics - DTC P0497: Evaporative Emission (EVAP) System Low Purge Flow Detected
General Description
The fuel vapor in the fuel tank is temporarily stored in the evaporative emission (EVAP) canister and drawn into the engine through the EVAP canister purge valve. The powertrain control module (PCM) controls the amount of vapor introduced into the engine by varying the duty cycle to the EVAP canister purge valve according to the condition of the engine.
[Purge flow confirmation]
When the pulse of the EVAP canister purge valve cycling is detected by the fuel tank pressure (FTP) sensor during purge flow (pulse method), the EVAP canister purge valve cycles normally (EVAP canister purge valve OPEN OK) and detects that the purge flow is normal.
- Purge flow is confirmed at each area of negative and positive manifold pressure, and when either area is abnormal, it is determined that there is an abnormality such as a loose or clogged purge line detected.
- When both negative and positive manifold pressure areas are abnormal, it is determined as an abnormality of the purge line or the EVAP canister purge valve opening.
[Abnormal part check]
When there is no pulse, there is either no purge flow or the EVAP canister purge valve is stuck closed.
[Abnormal purge flow]
When the condition of non-return valve A is abnormal, the detected abnormality is because of reverse flow.
- Purge flow check at negative pressure area -
[STEP 1]
The EVAP canister purge valve cycles normally (EVAP canister purge valve OPEN OK) and detects that the purge flow is normal when the pulse of the EVAP canister purge valve cycling is transmitted to the FTP sensor during purge flow (pulse method).
OK determination: Pulse exists (P145C OK)
- P0497 Purge flow OK
- P0496 EVAP canister purge valve stuck Closed check OK
NG determination: No pulse (P145C NG)
- Either purge flow P0497 abnormality or P0496 EVAP canister purge valve OPEN failure.
- In this case, classify the failure according to [STEP 2].
[STEP 2]
In case there is no pulse, it is determined either no purge flow or EVAP canister purge valve stuck closed as follows: When the FTP sensor fluctuates from negative pressure condition to atmospheric side pressure after the ignition switch is turned to LOCK (0): P0496 EVAP canister purge valve stuck open
When there is no fluctuation of the FTP sensor: P0497 purge flow NG
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Enable Conditions
Malfunction Threshold
The output from the fuel tank pressure sensor is 0.2 kPa (0.07 inHg, 2 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
1. Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on.
2. Let the engine idle for at least 59 seconds.
3. Drive the vehicle on boost for at least 14 seconds.
4. Turn the ignition switch to LOCK (0) for at least 10 seconds.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, 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.