What the E# (-1025) alarm means

The servo system detected an encoder fault on the indicated joint; position feedback cannot be trusted and the joint will not move. This is one of the faults our repair team handles on Omron SmartController (ACE / Viper / Cobra) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Encoder backup battery dead (absolute position lost)
  • Damaged encoder cable at a flex point
  • Failing encoder
  • Noise on the encoder signal
Field note: the first item on this list is what we find most often on real machines. Check it before you go deeper.

Step-by-step field fix

  1. Replace the encoder backup battery pack (see the robot user guide for location)
  2. Inspect the encoder cable along the arm flex path
  3. Clear the fault with the service utility (e.g. RSC_SET on Adept/Omron systems) if position data was lost
  4. Re-calibrate the joint against its mechanical reference
  5. Replace the encoder if faults return
Safety first: never bypass safety circuits or force contactors closed. If the alarm involves E-stop chains, brakes or drive power, and you are not a trained robot technician, contact a professional — wrong moves here can cost you a robot or an injury.

Still stuck? Get an engineer on the phone — right now

Tell us the alarm code, the robot model and what was happening when the alarm came up. Our engineers run these diagnostics every day, and remote diagnosis by phone or video call is free.

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Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Encoder & Position alarms

H# — High Temperature — Encoder (Joint N)
Other brands: we also keep field-fix libraries for ESTUN · INOVANCE · EFORT and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Omron E# (-1025) alarm mean?

The servo system detected an encoder fault on the indicated joint; position feedback cannot be trusted and the joint will not move. In field practice it belongs to the encoder & position family of faults.

QCan I clear a Omron E# (-1025) alarm myself?

Sometimes. Work through the step-by-step checks on this page — the first listed cause is what we find most often in the field. If the alarm returns after two attempts, or the fault involves power, brakes or safety circuits, stop and call a qualified robot service engineer.

QHow fast can a Henghuan engineer help?

On-site response in the Pearl River Delta within 30 minutes to 3 hours, across mainland China in 1-3 business days, and worldwide within 2-5 business days. Remote diagnosis by phone/WhatsApp/video is available immediately.

Written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your Omron documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Omron.