Nibe 222 Fault Code: Causes, Fixes & Repair Costs
What does the Nibe 222 fault code mean?
Alarm 222 on a NIBE system is a motor protection alarm: the outdoor unit has reported that its compressor motor protection operated — the device guarding the compressor against overcurrent, phase problems and overheating — and the compressor is blocked. Motor protection trips when the compressor works abnormally hard or its electrical supply misbehaves: seized or tight bearings, refrigerant conditions loading the motor (including liquid refrigerant returning to the compressor), voltage sags or phase loss, or the protection module itself failing. One reset after a possible supply blip is reasonable; a recurring 222 needs proper electrical and refrigerant-side diagnosis before the compressor pays the price.
General guidance only — not a substitute for professional advice, and not certified by an heat pump engineer. Always have your specific appliance assessed by a qualified professional. Any heat pump work must be carried out by an MCS-certified heat pump engineer. If you notice a refrigerant leak, a burning smell or water leaking from the unit, switch it off at the isolator and call an MCS-certified heat pump engineer. Refrigerant work must be carried out by an F-Gas registered engineer.
Common causes
- Supply voltage problems Common
Brownouts, sags or (on three-phase units) phase loss make the motor draw excess current until protection trips — check whether other appliances flickered at the same time.
- Compressor working abnormally hard Sometimes
Refrigerant conditions loading the motor — liquid return, extreme pressures — or mechanical tightness in an ageing compressor raise current beyond the protection threshold.
- Protection module or wiring fault Sometimes
The motor protection device and its wiring can fail and trip spuriously; diagnosed by measuring what the motor actually draws.
How to fix it
- Acknowledge the alarm once and observe DIY safe
Reset/acknowledge the alarm on the indoor display a single time. If it returns, stop resetting — the outdoor unit is reporting a genuine condition and repetition only stresses the compressor.
- Have a suitably qualified heat pump engineer complete the documented checks heat pump engineer
The engineer will measure the supply voltage and the compressor's actual running current, check the protection device and its wiring, and assess the refrigerant conditions the motor is working under — establishing whether the protection tripped honestly before any thought of overriding or replacing it. Any work on the sealed refrigerant circuit legally requires an F-Gas registered engineer; a NIBE-accredited (NIBE Pro) installer is the natural choice.
Parts you may need
- Motor protection module · from £80
- Compressor · from £600
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £120–£700, depending on the underlying cause.
Frequently asked questions
What does alarm 222 mean on my NIBE?
The outdoor unit's compressor motor protection tripped — the device guarding the compressor from overcurrent and overheating — and the compressor is blocked. One reset after a possible power blip is fine; a recurring alarm needs the supply, the protection device and the compressor's real load professionally measured.
Is my compressor failing?
Not necessarily — supply problems and protection-module faults trip the same alarm. But because a genuinely labouring compressor is among the possibilities, recurring 222s deserve prompt diagnosis rather than repeated resets; the compressor is the one part you cannot afford to sacrifice to impatience.
The alarm coincides with evening peaks — meaningful?
Quite possibly — local voltage sags at peak demand load motors measurably harder. An engineer logging the supply voltage across an evening can confirm it, and persistent undervoltage is worth raising with your network operator.