Error 31

Running belt did not reach the target speed within the allotted time.

Multiple, frequent speed changes - in older software, the speed attainment timer starts with first speed change request and does not reset for subsequent speed change requests before the timer expires, therefore the equipment may be in the midst of a speed change when the timer expires, this can result in an E31.
Excessive mechanical drag - belt / deck / roller wear or contamination, bearing damage, debris entrapment, etc. can result in speed performance degradation.
Treadmill with waxless deck.
Extreme use - combination of high speed and / or high user weight could result in this error.

Ensure that latest software is installed. Download the latest software https://www.halo.fitness/web/softwareDownload.html.
For Cybex R-Series treadmills with waxless deck built before 10/3/2018, install waxed deck part number 10055463-0002e
Inspect equipment for excessive drag, check belt and deck, steps, brake, motor and roller bearings, debris entrapment (on, in or under equipment), etc.
Interview staff - Determine use conditions at time of error, are or was there:
- Multiple equipment operating on single circuit
- Low line voltage (brownout)
- Extreme use: heavy user and / or high speed
- Extreme use: target speed exceeds user capability
- Extenuating circumstances that would cause high current draw
Note: above average current draw can result in E31 so consider any conditions that could raise current draw, cause could be related to use or environment.