DTC P145A: Evaporative Emission (EVAP) System Incorrect Purge Flow Detected: 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 boost area -

< Purge flow check >

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 (P145D OK)

• P145A Purge flow OK
• P0496 EVAP canister purge valve stuck Open check OK

NG determination: No pulse (P145D)

• Either purge flow P145A abnormality or P0496 EVAP canister purge valve stuck OPEN failure.
• In this case, When the purge flow check at P145C negative pressure area is determined as OK, or when P0496 EVAP canister purge valve is judged as normal according to the check after the ignition is turned off, after P145C is determined as abnormal, P145A boost area purge flow abnormality is determined.

* When P0496 is determined as normal after the ignition is turned off, determination of the P145C is also implemented after the ignition is turned off.

< Purge flow reverse flow failure P145B >

When the non-return valve A fails, boost pressure flows back to the tank side during purge control at boost.

At this time, the pulse wave of the FTP sensor is reversed from the normal phase. Time difference of the phase is calculated to determine the purge flow failure.