CAT ATS Sensing or Logic Fault

Generator starts and runs only during exercise but not during real power outages

Advertisements

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Advertisements

Possible Causes

ATS not sensing utility failure correctly, Incorrect voltage sensing configuration, Faulty ATS controller, Loose sensing wiring

How to Fix / Troubleshooting

Safety: Work inside the ATS only if qualified. Utility power is lethal.

  • Review ATS logs/indicators: Check if the ATS recorded recent utility failures and whether it attempted to start the generator.
  • Check sensing fuses: Inspect fuses protecting the utility sensing circuits in the ATS. Replace blown fuses after finding the cause.
  • Verify configuration: Ensure the ATS is configured for the correct utility voltage and phase configuration.

If the ATS does not respond to real outages but does exercise correctly, its controller may be defective and should be serviced or replaced by a CAT technician or electrician.

Advertisements

Repair Difficulty

Hard 4/5

Required Part

Automatic Transfer Switch Controller
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements