HAAS® Alarm 122 — REGEN OVERHEAT
Part of: our HAAS® alarm reference · covering 60 of the most common alarms.
What it means
The regen resistor (which dissipates braking energy from the drives as heat) has gone over its temperature limit.
Common causes
- Heavy braking pattern (lots of decel, lots of spindle stops)
- Regen resistor partially failed
- Cooling around the resistor blocked
What to check first
- Let the machine cool down for 15–20 minutes
- Check airflow around the regen resistor
- Repeat alarms — service call to test/replace the resistor
Prevention
Cabinet maintenance is the quiet hero. A 5-minute filter clean every fortnight prevents the vast majority of cabinet-temperature and drive-temperature alarms. Replace cabinet filters at the schedule the manual specifies, not when they look clogged — by then they're already restricting airflow.
If you’re still stuck
If you’ve worked through the checks above and the alarm hasn’t cleared — or if it cleared and came back — that’s the point to call. Persistent alarms after a reset usually mean a real component fault, and pushing through them risks turning a simple repair into a bigger one. Keith covers HAAS® breakdowns across the UK with same-day phone diagnosis.
A note on this guide. Alarm wording and numbering can vary by HAAS® machine model and software revision. The descriptions here are written in plain English to help you understand what the machine is reporting and what to check first — they’re not a substitute for the official HAAS® operator manual or for a qualified service engineer’s diagnosis. Always confirm the exact alarm message on your screen and consult your machine’s documentation before attempting any repair.