What the SRVO-038 alarm means

The controller detected a pulse count mismatch for the axis between power cycles - the feedback position jumped unexpectedly. This is one of the faults our repair team handles most often — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Battery voltage dropped during power-off
  • Encoder cable intermittently disconnected
  • Pulse coder internal fault
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. Check battery voltage and encoder connectors first
  2. RES_1PA reset, cycle power
  3. Re-master the axis and verify against witness marks
  4. If the alarm returns repeatedly, replace the pulse coder (motor assembly)
Safety first: never bypass safety circuits or force contactors closed. If the alarm involves E-stop chains or servo 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.

Get a Free Remote Diagnosis See Repair Services

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

Related Battery & Mastering alarms

SRVO-062 — BZAL Alarm (Group / Axis) SRVO-065 — BLAL Alarm - Battery Voltage Low SRVO-075 — Pulse Position Mismatch SRVO-027 — Robot Not Mastered
Other brands: see our KUKA, ABB, Yaskawa and Universal Robots field-fix libraries — or the full 10-brand hub.

Frequently asked questions

QWhat does the FANUC SRVO-038 alarm mean?

The controller detected a pulse count mismatch for the axis between power cycles - the feedback position jumped unexpectedly. In field practice it belongs to the battery & mastering family of faults.

QCan I clear a FANUC SRVO-038 alarm myself?

Sometimes. Follow the step-by-step checks on this page — start with the first cause listed, which is what we find most often in the field. If the alarm returns after two attempts, or the fault involves power/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 version — when in doubt, check your FANUC documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by FANUC.