DTC P145F: General Description

Courtesy of HONDA, U.S.A., INC.

Courtesy of HONDA, U.S.A., INC.

Courtesy of HONDA, U.S.A., INC.

The powertrain control module (PCM) starts the evaporative emission (EVAP) system diagnosis after the vehicle has been driven with certain condition and turned to the OFF (LOCK) mode with all other enable conditions (engine coolant temperature, vehicle soak duration, etc.) are met. The EVAP system diagnosis is performed by reducing pressure with the EVAP leak check module vacuum pump that is equipped between the EVAP canister and atmosphere.

EVAP leak check module operation flow

• Reference pressure measurement: Checks the status of the EVAP leak check module or determines the diagnosis termination if the system is OK.
• System pressure reduction: Reduces pressure in the EVAP system and measures the ultimate pressure.
• Reference pressure re-measurement: Determines the leak of the system by comparing the ultimate pressure of the system pressure reduction with the reference pressure re-measurement.

  The re-measurement is done twice considering the change in the characteristics of the EVAP leak check module vacuum pump during detection.

Reference pressure is a pressure reduced by the reference orifice (#40 equivalent) in the EVAP leak check module, and used to check for leak by comparing with the system reduction pressure.

If the difference between the maximum pressure and the minimum pressure during the reference pressure measurement is a specified value, the PCM detects a malfunction and stores a DTC.