F13
Glow-worm
External Control / eBUS Communication Fault
Boiler displays F13, may not respond to room thermostat or external controls
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
Incorrect wiring of Glow-worm Climastat or MiGo controls, Short circuit on eBUS terminals, Faulty external control, PCB eBUS circuit fault
How to Fix / Troubleshooting
Safety: Isolate power before touching any wiring terminals.
- Check control wiring: Remove the boiler front panel and inspect the eBUS or room stat terminals. Ensure no bare wires are touching and polarity (if required) is correct.
- Temporarily disconnect controls: With power off, disconnect external controls from the boiler and fit the factory link (if provided). Restore power and see if the boiler runs without F13. If it does, the external control or wiring is at fault.
- Inspect external devices: Check the Glow-worm controller for damage, water ingress, or flat batteries (if wireless).
- Engineer tasks:
- Test eBUS voltage and signal at the boiler terminals.
- Check for shorts or incorrect connections in the control cable route.
- Replace faulty control or repair wiring as needed.
Never connect mains voltage to low-voltage eBUS terminals; this can destroy the PCB.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
Room Thermostat / eBUS Controller
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements