Q: a sharp 1.6L car, carrying CDF engine, driving more than 70000 kilometers, the normal running always left to the left, and power to the red lights occasionally light. I have done four rounds of positioning for many times, and it is not valid. There is no accident in the car. There is no possibility of external factors causing deformation of steering mechanism. Please help analyze! Answer: the car is equipped with an electric power assisted steering system. Once the system fails, there are generally three reasons besides mechanical reasons. (1) the steering torque sensor G269 is bad; second, the steering angle sensor G85 is bad; third, the steering power control unit is not good. According to the overhaul principle of fault code priority, you should first enter the power steering system to troubleshooting fault codes. I have seen one of these maintenance cases. There is one type of car that is the same type as you, which is to turn out the fault code 00573 from the power steering system and turn to the electrical fault in the torque sensor G269 circuit. The steering torque sensor G269 of the vehicle is integrated in the steering assist control unit J500. If the sensor is really a problem, it needs to replace the electric steering gear assembly. In order to avoid misdiagnosis, we first turn the electric power - controlled power to the part of the electrical plug, that is, do not use electronic control power to test the car, the result of the car straight, no longer run to the left. Therefore, it is diagnosed as an electric power assisted steering gear failure and needs to replace the power steering gear assembly. After the replacement of the steering engine assembly, we need to use the equipment to enter and visit approval. Before 2008, the car entered 31857 and 40168 after 2008, then enter the basic setting, input 60, activate the point, and beat the steering wheel to the end, then go to the right, then pull the key after the extinguishing, and then restart the test. The result is found to be found out. The barrier is still, still running to the left. This shows that the reason for deviation is not on the electric power steering gear assembly. Is it a mechanical fault? So the length of the cross bar on both sides is checked directly, the difference between the length of the length and the center position of the steering wheel and the center position of the steering column is dozens of degrees, which should be the reason for the vehicle to always run off. The length of the left and right pull rod is readjusted, and the center position of the steering wheel and the steering column is installed, and then a four wheel alignment is remade, and the vehicle is running back to normal and no longer running. Because the electric power steering system has the active return function, that is, when the vehicle runs in a straight line, if the steering angle sensor G85 detects that the steering wheel is not at the center position at 0 point, then J500 will control the power steering motor (V187) according to the signal of the G85, thus giving a back torque to the steering wheel, so that the steering wheel can be returned to the steering wheel. Center position. Although the central position of the steering wheel and the steering column is misplaced, the car can run in a straight line when the four wheel alignment is adjusted to the normal parameters. However, once the driver turns the steering wheel straight, the steering angle sensor G85 detects the left or right deviation of the steering angle, and the electronic control system receives the deviation information, and will be actively adjusted. As a result, the vehicles that are clearly not run off will run off. The vehicle is the steering angle sensor G85 detecting the steering angle to the right deviation dozens of degrees, the power steering control unit J500 according to the G85 signal, control the power steering motor (V187) work, providing the left back moment, resulting in the vehicle's active deviation to the left.