H63 on a Panasonic heat pump: Abnormal low pressure sensor
Short answer
On a Panasonic heat pump, H63 means: Abnormal low pressure sensor. 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: Abnormal low pressure sensor.
Part involved: Outdoor low pressure sensor.
When it shows: During operation of cooling and heating, when the outdoor low pressure sensor output signal is 0 Vdc or 5 Vdc. Service-manual table judgement: 4 times in 20 minutes (J MDC, J MXC, L).
Likely causes:
- 1 Faulty connector connection. 2 Faulty low pressure sensor. 3 Faulty outdoor unit PCB (main). (K manual self-diagnosis p.237; J/L tables: low pressure sensor defective or disconnected.).
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 the Panasonic documents opened; protection counters lock out after the stated number of occurrences.
Manual reset: User: 'Error Reset' in the remote-controller Quick Menu (H/J/K/L controllers) or OFF/ON; engineer must clear the underlying cause (service manuals: 'When error happens, the power has to be reset').
What you can check
- Read and note the code shown blinking on the remote controller (also stored under System Check > Error history). Per the Panasonic operating instructions the user may switch the system OFF/ON at the remote controller and use 'Error Reset' in the Quick Menu; if the code returns, leave the system and contact the installer (UK user guide lists Panasonic technical support as the fallback).
What the engineer will check
- Check low pressure sensor connector and output voltage (0 V or 5 V output indicates fault); check refrigerant pressure with gauges; replace sensor or outdoor PCB.
Who to ask for: F-gas certified refrigeration / heat pump engineer (Panasonic-trained).
Certification: UK F-gas certification (Category I) for any refrigerant-circuit work; flammable-refrigerant competence for R32 (J/K) and R290 (L/M) units.
What you might notice
Sources
- Service Manual Mono Bloc Unit WH-MDC05J3E5 / WH-MDC07J3E5 / WH-MDC09J3E5 (Order No PAPAMY2003034CE) ↗ · PAPAMY2003034CE · page 164 (error codes table) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026