F46 on a Panasonic heat pump: Outdoor Current Transformer open circuit
Short answer
On a Panasonic heat pump, F46 means: Outdoor Current Transformer open circuit. 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: Outdoor Current Transformer open circuit.
Part involved: Current transformer (CT) on outdoor PCB; compressor.
When it shows: A current transformer (CT) open circuit is detected by checking the compressor running frequency ( rated frequency) and CT detected input current (< 0.65 A) for continuously 20 seconds.
Likely causes:
- 1 CT defective. 2 Faulty outdoor unit PCB (main). 3 Compressor defective (low compression).
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 CT and outdoor PCB; check compressor compression; check refrigerant charge.
Who to ask for: Heat pump engineer with electrical competence.
Certification: Electrical work to BS 7671 by a competent person; F-gas certification if the refrigerant circuit is opened.
What you might notice
Sources
- Service Manual Hydromodule WH-SDC0509L3E5/L6E5 with WH-WDG05LE5/07LE5/09LE5 (Order No PAPAMY2307068CE) ↗ · PAPAMY2307068CE · page 190 (error codes table); 239 (self-diagnosis) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026