E2 on an Ideal Heating HP290: No connection Outdoor PCB to User Interface
Short answer
On an Ideal Heating heat pump, E2 means: No connection Outdoor PCB to User Interface. 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: No connection Outdoor PCB to User Interface.
Part involved: user interface / 2-way comms cable.
Likely causes:
- Two-way wiring between outdoor unit and indoor unit, or indoor PCB to user interface PCB, incorrectly connected; faulty user interface; outdoor PCB fault.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Note the code or fault message shown on the controller/Halo and when it appeared; check the heat pump's isolator and consumer-unit breaker are on. If the fault clears after the installer-approved restart via the controller and does not return, note it for the next service; if it returns, call an engineer.
What the engineer will check
- Check 2-way wiring outdoor-indoor and indoor PCB-user interface; replace user interface, then outdoor PCB.
Who to ask for: Heat pump engineer competent with R290 (A3, highly flammable); refrigerant-circuit work requires Cat I/II F-gas plus City & Guilds 6187-21 or equivalent (I&M p.93 warning).
Certification: F-gas Cat I/II + C&G 6187-21 (R290) for refrigerant work; electrical work by competent person.
Sources
- HP290 Monobloc Heat Pump System - Installation & Maintenance (UIN 240080 A09) ↗ · UIN 240080 A09 · page 98 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026