A 2012 Honda civic car with 1.8Li-VTEC engine. The vehicle is an accident vehicle. After repair, it turns heavy to the left. Inspection and analysis: according to the fault phenomenon, the suspected failure point may be in suspension system or steering system. The maintenance personnel who asked about the accident of the car learned that the car had changed the steering gear and sub frame, and disassembled and installed the meter. First check the four wheel positioning, found that the left front wheel obliquity value is larger, beyond the maintenance limit, then dismantling the steering joint and the new parts after the comparison, found a slight deformation, the change of the left front wheel tilt angle after the change to the standard range, but the test found that the failure is still. Lift the car with a lifting machine, remove the fixed bolt of the steering gear and the steering knuckle, disconnect the steering section and test the car. The fault still exists, indicating that the suspension system has trouble. After understanding, compared with the old car, the 2012 production car has improved the steering system from the hydraulic power steering to the electronic power steering system. The system is composed of EPS control device, torque sensor, steering angle sensor, steering assembly and so on. Connecting HDS reads the fault code, does not find fault code, then reads the data flow of the electronic control steering system, and finds that the steering torque is 0.27 N. M when the steering wheel is in the middle position, and the normal should be 0 N. M, which will cause the steering gear to always have a right power, so the force becomes resistance when turning left to the left. The left turn is heavier than the right turn to the right. The search maintenance manual analyses the source of abnormal steering force and learns that the initial position of the steering angle should be studied after the change of the steering gear, which is not caused by the learning of the initial position of the steering angle. Elimination method: according to the steps in the maintenance manual, learn the initial position of the steering angle.