What Does This Error Mean?

A NordicTrack treadmill that will not start is almost always caused by the magnetic safety key not being inserted or not making proper contact with the console sensor. Insert the key clip firmly into the slot until it clicks. If the treadmill randomly stops during use, the key is vibrating loose — use a safety clip leash or replace the key.

Affected Models

NordicTrack Commercial 1750
NordicTrack T 6.5 S
NordicTrack T 8.5 S
NordicTrack EXP 7i
All NordicTrack treadmills with magnetic safety key

Common Causes

Safety key not inserted into the console slot
Safety key magnet worn — reduced magnetic strength no longer detected by sensor
Safety key slot sensor dirty or corroded
Safety key vibrating loose during high-intensity running
Wrong safety key — key from a different treadmill model may not be compatible

How to Fix It

Insert the safety key firmly into the console slot.

The safety key's metal clip slides into a slot on the console, usually marked with a key or stop symbol. Push it in firmly until it seats fully — the console should power on or allow the belt to start. A partially inserted key will not activate the reed switch sensor.
Attach the safety leash to yourself.

The safety key has a cord leash designed to attach to your clothing or waistband. For normal use, the leash should be loose enough that you can move freely but taut enough to pull the key if you fall or step off. Do not remove the leash — it is the emergency stop mechanism.
Test with the key held stationary.

If the treadmill stops randomly during a run, hold the safety key in place manually while running and see if the stops cease. If they do, the key is vibrating loose from belt/frame vibration — use a piece of foam tape to add friction in the key slot, or replace the key.
Clean the safety key slot.

Use a dry cotton swab to clean inside the safety key slot. Dust and lint can accumulate and reduce the contact between the key magnet and the reed switch sensor. A clean slot improves detection reliability.
Replace the safety key.

Safety keys are inexpensive wear items — the magnets weaken over years of use. Order a replacement NordicTrack safety key that matches your model (check the underside of your treadmill for the model number). Generic universal treadmill keys may not be compatible — use a genuine NordicTrack replacement.

When to Call a Professional

If a new, correct-model safety key is inserted firmly but the console still does not power on, the safety key sensor (reed switch) on the console circuit board may be faulty.