What it means
The STS has detected an internal controller fault associated with the watchdog function.
This entry is tied to the exact STS message family documented by Sullair. The same words can mean something different on another controller generation, so confirm the displayed message and machine documentation before acting.
Likely causes
- Internal controller fault
Operator-safe first checks
- Record the exact message and whether other faults occurred at the same time.
- Preserve event-history information before cycling power if site procedure allows.
Trained maintenance / service checks
- Follow Sullair service guidance for controller diagnostics.
- Do not substitute parts or reinitialize the controller without the correct machine configuration.
Reset or keep running?
Do not use repeated resets as a substitute for diagnosis. If the condition involves electrical power, a motor overload, high pressure, loss of cooling, abnormal temperature, or a safety circuit, correct the underlying problem before returning the compressor to service.
Source confidence
OEM VERIFIED
This message and its troubleshooting direction are traced to the Sullair STS controller troubleshooting guide.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page: 30.