Engine PCM fault P2402; “Evap system leak detection control circuit high”. The PCM has detected a high load current in this circuit.
Mazda recall 3205G may correct this problem;
“On some 2004 MAZDA6 vehicles equipped with 3.0 liter engines, the pump control circuit failure detection ability may be lower than required regulations due to the initial design of the Powertrain Control Module (PCM) evaporative emission leak monitoring system circuit. If this failure occurs, the vehicle does not meet the OBD-II requirements.”
Check with your Mazda dealer to see if your vehicle has incomplete recalls.