What the 4154 alarm means

The temperature of the regeneration (braking) resistor exceeded its limit; the controller limits or stops motion to prevent the resistor from burning out. This is one of the faults our repair team handles on Epson RC90 / RC700 (EPSON RC+) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Robot duty cycle too high for the installed resistor
  • Acceleration/deceleration too aggressive
  • Aging or degraded resistor
  • High ambient temperature around the DPB board
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. Let the resistor cool and retry
  2. Lengthen waiting time or reduce acceleration values
  3. Lower the overall motion duty
  4. If the alarm persists at normal duty, replace the DPB board/resistor
  5. Check ventilation around the controller
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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Related Drive & Power Stage alarms

4152 — Relay Welding Error of Main Circuit 5040 — Motor Torque Output Failure — High Power State 5048 — Overvoltage of Main Power Circuit 5049 — Overcurrent of Motor Driver 5054 — Motor Overload (Duty)
Other brands: we also keep field-fix libraries for Nachi · Omron · ESTUN and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Epson 4154 alarm mean?

The temperature of the regeneration (braking) resistor exceeded its limit; the controller limits or stops motion to prevent the resistor from burning out. In field practice it belongs to the drive & power stage family of faults.

QCan I clear a Epson 4154 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 Epson documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Epson.