Error code
1b Outdoor temperature sensor fault
How it shows on the unit Recorded as a check code after 4 detections; the display does not flash
Applies to 4 models
RAS-25PKVSG-ND, RAS-35PKVSG-ND, RAS-25PAVSG-ND, RAS-35PAVSG-ND
What this means
The TO outdoor-temperature sensor is disconnected or short-circuited. The unit keeps operating; the fault is only recorded in the check-code memory.
When to call a technician
This fault involves refrigerant, pressure, or electrical work that must be handled by a certified technician under EU F-gas rules. Do not attempt to open the refrigerant circuit, access mains wiring, or adjust pressure components yourself. Contact a qualified installer or servicer for this one.
Using Claude Code or Meta Muse? Connect HeatPump AI and ask it about 1b.