Function Explanation (DTC Detection Outline)
WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.
- The pressure change of the evaporative gas passage is measured using barometric pressure and intake manifold vacuum to detect evaporative gas leakage. The PCM introduces barometric pressure or intake manifold vacuum into the evaporative gas passage by opening/closing the purge solenoid valve and CV solenoid valve, and measures the pressure change using the fuel tank pressure sensor.
P0455:00
- The PCM closes the CV solenoid valve while the vehicle is being driven, and seals the fuel tank. The PCM introduces intake manifold vacuum into the fuel tank and measures the pressure change of the fuel tank using the fuel tank pressure sensor by opening the purge solenoid valve after sealing the fuel tank. If the pressure of the fuel tank does not reach the target value after the specified time has elapsed since the pressure was measured, the PCM determines that there is an evaporative gas leakage. If the PCM determines that refueling is not performed before the engine starts according to the result of the refuel determination, DTC P0455:00 is stored (if the PCM determines that refueling is performed, DTC P0457:00 is stored).
- If the fuel tank level increases after the engine starts, the PCM determines that refueling was performed by comparing the fuel tank level before one drive cycle with the fuel tank level after engine start.
P0442:00
- The PCM closes the purge solenoid valve after diagnosing (normal) DTC P0455:00, and seals the fuel tank. The pressure change of the fuel tank is measured by the fuel tank pressure sensor after the fuel tank is sealed. The PCM determines a temporary malfunction if the pressure change is the specified value or more after the specified time has elapsed since the pressure was measured. If the CV solenoid valve is open after determining a temporary malfunction and the pressure change (increase) of the fuel tank is the specified value or less, the PCM determines that there is an evaporative gas leakage and a DTC is stored.
P0456:00
- After the engine stops with the preconditions met, the PCM closes the CV solenoid valve and seals the fuel tank. The pressure change of the fuel tank is measured by the fuel tank pressure sensor after the fuel tank is sealed. The PCM determines a temporary malfunction when the pressure change is the specified value or less after the specified time has elapsed since the pressure was measured. If the CV solenoid valve is open after determining a temporary malfunction and the pressure change of the fuel tank is the specified value or less, the PCM determines that there is an evaporative gas leakage and a DTC is stored.