Bonaire fault code E05
Ambient temp sensor fault.
What E05 actually means
The ambient temperature sensor has gone open-circuit or out of range. The unit no longer knows what the outside temperature is, which affects how it decides to run.
What causes it
- Sensor failed, which they do after enough summers on a roof
- Sensor wiring damaged by UV or by weather
- Terminal corroded
- Water ingress at the sensor connection
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.
- Nothing. It is a roof-mounted sensor on a low-voltage circuit
What we check on site
So you know what you’re paying for.
- Sensor resistance against the temperature table
- Wiring continuity and insulation
- Terminal inspection for corrosion
- Controller input verification
Can you keep using it?
It will run, usually in a default mode, and it will cool. It just will not manage itself as well as it should. Fix it at the next service rather than treating it as an emergency.
What the fix usually involves
Sensor swap. Stocked part, quick job, and worth doing at the same time as a pre-summer service rather than as its own call-out.
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 →