It has an error 15 that keeps poping up - Precor C956 Treadmill with Cardio Theater Option (Used)

Precor Error 15, AC Input Voltage Too High Probable Cause 1. AC input voltage is incorrect.
2. AC input voltage transients. Transients can be caused by lightning strikes or by other pieces of equipment sharing the unit's AC power.
Corrective Action

1. Verify AC feed into the building's circuit breaker is correct and connected to the proper transformer tap.
2. Ensure the AC grounding for the unit's outlet is good and verify the unit is connected to an isolated and dedicated 20 amp circuit.