LP1 on a Kensa heat pump: Low refrigerant pressure in suction gas pipe (P3)
Short answer
On a Kensa heat pump, LP1 means: Low refrigerant pressure in suction gas pipe (P3). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 4 sources
What it means
The manual says: Low refrigerant pressure in suction gas pipe (P3).
Part involved: P3 suction pressure / ground circuit.
When it shows: Error level per manual: Fault.
Likely causes:
- Ground-side flow restriction (often with FGH1), frozen unit / insufficient antifreeze, ground pump failure; can occur on first run or after long idle.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Note the code shown on the controller/LED; check the heat pump isolator and consumer-unit breaker are on; check thermostat/timer settings.
What the engineer will check
- Follow Kensa fault table actions: Ground-side flow restriction (often with FGH1), frozen unit / insufficient antifreeze, ground pump failure; can occur on first run or after long idle. Check ground flow and pump, antifreeze, allow defrost if frozen; check refrigerant charge if persistent.
Who to ask for: Refrigeration engineer (F-gas certified) / Kensa technical support.
Certification: F-gas Category I (refrigerant circuit work); MCS-certified GSHP installer.
What you might notice
Sources
- Kensa Evo Heat Pump Installation manual ↗ · V32 · page 51 · Reviewed 23 September 2026
- Q80 Series Heat Pump Operational Manual ↗ · Version 2 · page 24 · Reviewed 23 September 2026
- Shoebox Heat Pump Operational Manual (User Manual) ↗ · Version 8 · page 27 · Reviewed 23 September 2026
- Kensa Shoebox NX heat pump Installation manual ↗ · V12 · page 41 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026