What Does This Error Mean?

Advice UPS fault light on means the UPS has detected a hardware or battery fault requiring attention. Check the front panel display for a fault code, then refer to the manual. The most common causes are battery failure, overload, or over-temperature.

Affected Models

Advice UPS Line-Interactive Series
Advice UPS Online Series
Advice UPS (all models)

Common Causes

Battery fault — battery has failed or has been disconnected
Overload condition — connected load exceeds rated output
Over-temperature — UPS internal temperature too high
Output voltage fault — inverter producing out-of-range voltage
Input voltage out of range — mains voltage outside acceptable limits for the UPS model

How to Fix It

Read the fault code from the front panel.

Advice UPS displays show a fault code number or a combination of LED patterns that identify the specific fault. Note the code exactly — for example, F01, F02, or a specific blinking pattern. Look up the code in the UPS user manual to identify the fault type.
Check for overload.

If the fault is overload-related, the load indicator (% or watts) will show above 100%. Disconnect non-essential equipment until the load indicator drops below 80%. The fault light should clear and the UPS should return to normal mode.
Check for overheating.

Place your hand near the UPS ventilation slots — excessive heat indicates an over-temperature fault. Move the UPS to a cool, well-ventilated area with 20cm clearance on all sides. Wait 20 minutes for cooling, then cycle power.
Test the battery.

A battery fault is the most common cause of a fault indicator. Disconnect the UPS from mains, remove the battery, and measure its voltage with a multimeter. A 12V battery below 10V has failed and needs replacement.
Reset the UPS after resolving the fault.

After addressing the root cause (reducing load, cooling, or replacing battery), power off the UPS completely. Wait 30 seconds, then power on. The fault light should clear on startup if the underlying issue has been resolved.

When to Call a Professional

If the fault light remains on after clearing overload, cooling the unit, and replacing the battery, the UPS inverter or control electronics may have failed. Contact Advice support or a certified UPS service center.