Reebok One gt30 treadmill e3 error

Reebok treadmill error e3 on motor speed sensor.
The sensor is a infrared beam between the 2 black bits that the motor fan edge runs in been and if the beam is blocked by dust or something the motor will speed up until max and cut off on error e3.
It may be just dust on it I just had it cleaned and reposition to the closest as possible to the fan. It reads on so far have done some tests and it's running fine but after if you had this problem make sure you always use the red safety cable and if you feel that something is wrong pull on it. this problem can cause a treadmill to speed up uncontrollably until it takes a while to stop sometimes best fix would be to buy a new sensor or have it serviced by rebok engineer's.