Advanced Diagnostics

Advanced Diagnostics

DTC P145C: Evaporative Emission (EVAP) System Purge Flow Malfunction (Vacuum Purge)





















General Description
The fuel vapor in the fuel tank is stored in the canister temporarily and introduced into the engine through the evaporative emission (EVAP) canister purge valve. The powertrain control module (PCM) controls the vapor amount introduced in the engine by duty cycling the EVAP canister purge valve.

[Purge flow confirmation]
When the pulse of the EVAP canister purge valve cycling is detected by the fuel tank pressure (FTP) sensor by the 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 open.

[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 (no boost) 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 by the purge flow (pulse method).

OK determination: Pulse exists (P145C OK)
- P0497 Purge flow OK
- P0496 EVAP canister purge valve stuck Open 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 open as follows:
When the FTP sensor fluctuates from negative pressure to atmospheric 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 pulses detected by the fuel tank pressure sensor are 0.1 % or less for at least 13 seconds (negative pressure (no boost) area).

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 13 seconds.
4. Turn the ignition switch to LOCK (0) for at least 10 seconds.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected during the first drive cycle, a Temporary DTC is stored in the PCM memory. If the malfunction recurs during the next (second) drive cycle, 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.