Alarm guide · Yaskawa · Updated October 2026
Yaskawa A.860 alarm: encoder overheat
Yaskawa A.860 means the encoder overheated. Check motor loading and ambient temperature, then the encoder.
By Suresh Sankaran, founder of Star Automations, servo motor repair since 1998.
What the alarm means
The encoder reported a temperature above its limit. Alarm numbers and wording can differ between series, so confirm with the manual for your unit.
Common causes
- Motor overloaded for long periods
- High ambient temperature or poor ventilation
- Heat from the machine into the motor
- Encoder fault
- Bearing friction heating the motor
Safe first checks
General guidance only. Follow the drive manual and your site's electrical safety rules. Power off, and let the DC bus discharge, before touching connectors.
- Note the exact alarm code and when it appears: at power-up, at start, or under load.
- Power off and turn the shaft by hand if safe: it should turn smoothly.
- Check the motor cable, encoder cable and connectors for damage and loose contacts.
- Check what changed recently: load, speed, settings, cables or a replaced part.
When to send it for repair
A motor that runs hot on a normal load should be inspected for bearings and winding.
We test every motor on our Universal Servo Motor Repair Equipment, which reads and aligns the feedback and runs the motor under load without the original drive.
See Yaskawa servo motor repair, Yaskawa encoder repair and Yaskawa servo drive repair.
Questions
Can it be the sensor only?
Yes, an encoder fault can report overheat. Bench testing separates the cases.
How long does repair take?
Emergency repair is done the same day where the fault and parts allow, urgent in 3 working days and standard in 7 working days, counted from when the unit reaches our bench and the quote is approved. Every unit returns with a printed test report.
Can I get an exchange unit?
If we hold a matching unit, Servo Swap ships a tested exchange unit while yours is repaired. Mark "line down" on the request form and add the part number.