What the 12005 alarm means

The temperature sensor circuit of the regenerative ballast (braking) resistor reads open, so the controller cannot verify braking resistor health and may limit or stop motion. This is one of the faults our repair team handles on KUKA KRC2 / KRC4 / KRC5 (KSS) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Sensor wire disconnected at the CCU or at the resistor
  • Broken temperature sensor
  • Wrong plug position on the CCU
  • Genuine resistor overheat after a high-duty cycle
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, then check the sensor connector at the CCU and at the resistor
  2. Reseat or repair the sensor wiring
  3. Measure the sensor resistance and replace it if open
  4. Verify the cell duty cycle is not forcing continuous regeneration
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 Drive & Power Stage alarms

26012 — General Servo Error (Drive N) 26013 — General Inverter Failure (Drive N) 26107 — KSP DC Link Overvoltage (Axis N) 26108 — KSP DC Link Undervoltage (Axis N) 26111 — KSP Device Overtemperature (Axis N) 26122 — KSP Braking Resistor Fault (Axis N)
Other brands: we also keep field-fix libraries for ABB · Yaskawa · Universal Robots and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the KUKA 12005 alarm mean?

The temperature sensor circuit of the regenerative ballast (braking) resistor reads open, so the controller cannot verify braking resistor health and may limit or stop motion. In field practice it belongs to the drive & power stage family of faults.

QCan I clear a KUKA 12005 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 KUKA documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by KUKA.