The total mileage of a Hainan Mazda car is automatically extinguished during normal driving, and the engine can not start again. Check the fuel supply system normal, use the multimeter to measure the resistance of the crankshaft position sensor is Omega, belong to the normal range, start the engine, check the output voltage of the crankshaft position sensor, low. The gap between the sensing head and the trigger wheel is reduced, the output voltage rises, but it is still unable to start. It is suspected that the magnetic field of the crankshaft position sensor becomes weaker, so a magnet with stronger magnetism is placed behind the sensor and the engine can start. The magnet is bonded to the rear of the sensor with epoxy resin and the vehicle can run normally.