Many treadmills have an incline feature. This feature is a mechanical device. Even the best mechanical devices stop working from time to time. The problem might be as easy as the incline icon needs recalibration or it could mean that you need to replace the motor. No matter what is causing it, the treadmill needs to be repaired for safe use.
Calibrate the Incline Icon
Insert the safety key. Push the "Stop" and the arrow up for speed keys at the same time.
Push the "Stop" key again. A message will pop up on the display stating the unit has passed the EPROM test. Messages can be "EP:2P," "PASS" or "FP," depending on the model you have.
Push the "Incline" key and the machine will automatically recalibrate.
Push the "Stop" button and remove the safety key.
Check For Motor Problems
Inspect the wires that run from the incline sensor to the power board with your multimeter, a handheld electronic measuring unit. If the meter readout panel shows is a small amount of voltage in the wires, then the incline needs to be recalibrated once again. If you see a blinking "--" in the incline window, the unit needs to be calibrated again. If that blinking dashes are not present, then the incline sensor needs to be replaced. Refer to the owner's manual for information on ordering a new sensor.
Check the wires that feed voltage to the incline motor with your multimeter. If the multimeter reads 120 volts, then the motor needs to be replaced. Refer to the owner's manual for customer service information.
Run the motor and observe it. If it only moves a little, it could be jammed. Refer to the owner's manual for customer service.