Bonaire fault code E12
Comms error (integrated system).
What E12 actually means
Communication error between the wall controller and the roof unit on an integrated system. Both ends may be fine; the message between them is not arriving.
What causes it
- Loose terminal at the controller or at the roof unit
- Comms cable damaged, sometimes by later roof work or by rodents
- Water ingress at a roof junction
- Controller or roof board fault
Most likely first. That order is from what we actually find on site, not from the manual.
Safe to check yourself
No tools, no covers off, nothing to do with gas, refrigerant or wiring.
- Turn the system off at the isolation switch for a minute and back on
- Check the controller lights up at all
What we check on site
So you know what you’re paying for.
- Continuity and voltage on the comms run
- Terminal inspection at both ends, especially the roof end
- Controller substitution
- Board comms diagnostics
Can you keep using it?
It will not run properly with comms down. Nothing unsafe about it, and on an integrated gas-and-evap system it is worth knowing this can knock out the heating side too.
What the fix usually involves
Usually a terminal or a damaged cable at the roof end, where weather gets at it. Fixed on the first visit in most cases.
Is it worth fixing?
That depends almost entirely on how old the unit is. Past about ten years on hot water and gas heating, and twelve on aircon, a significant repair usually costs more per remaining year than a replacement does — and it’s the same point at which the VEU rebate is worth the most, because old inefficient appliances are exactly what the scheme pays to remove. If yours is young and the fault is a component, we’ll fix it and say so.
Repair or replace? The 10-year rule, and what the rebate is worth →