E01 on a Grant Aerona 290: Communication error between Smart Controller wiring centre and heat pump (error shown on touch screen)
Short answer
On a Grant heat pump, E01 means: Communication error between Smart Controller wiring centre and heat pump (error shown on touch screen). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Communication error between Smart Controller wiring centre and heat pump (error shown on touch screen).
Part involved: wiring centre to heat pump Modbus connection.
Likely causes:
- Connection fault between the wiring centre and the heat pump.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Not stated in DOC 0204.
Manual reset: DOC 0204 s11.1: once the fault is resolved, reset by turning the unit OFF and back ON; s11.5: power cycle can be done from the Aerona Smart Controller touchscreen instead of the external isolator (installer procedure).
What you can check
- Note the exact code shown on the controller display and tell your installer or Grant-trained engineer.
- Check the heat pump isolator switch and the consumer-unit breaker/RCD for the heat pump are ON (do not repeatedly reset a tripping breaker).
What the engineer will check
- Check the connections between the wiring centre and heat pump (DOC 0204 s9.1.5).
- Check Modbus wiring connection and polarity (see Smart Controller DOC 0203 s12.1.2 'No communication with the heat pump module').
Who to ask for: Grant-trained heat pump engineer.
What you might notice
What owners and engineers report
5 owner and engineer reports mention this.
- Controller / thermostat problem on the Aerona 290: 5 reports
Sources
- Grant Aerona 290 Air to Water Air Source Heat Pump Range - Installation & Operating Instructions (UK DOC 0204) ↗ · Rev 1.9 · page 48 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026