Advanced Diagnostics
Advanced Diagnostics - DTC P145D: Evaporative Emission (EVAP) System Purge Flow Malfunction (Jet Purge)
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 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 during 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 switch is turned to LOCK (0), after P145C is determined as abnormal, P145A boost area purge flow abnormality is determined.
- When P0496 is determined as normal after the ignition switch is turned to LOCK (0), determination of the P145C is also implemented after the ignition switch is turned to LOCK (0).
[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.
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Enable Conditions
Malfunction Threshold
The pulse from the fuel tank pressure sensor is 50 % or less for at least 14 seconds (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 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.