P17 on a Trianco heat pump: Syst1: Suction Temp Sensor Fault
Short answer
On a Trianco heat pump, P17 means: Syst1: Suction Temp Sensor Fault. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 4 sources
What it means
On the Activair Commercial R290 50kW (FG9550)
The manual says: Syst1: Suction Temp Sensor Fault.
Part involved: temperature sensor/thermistor.
Likely causes:
- The temperature sensor is open or short circuited.
On the Activair High Temperature R290 (5/9/15/22kW)
The manual says: Water Outlet Temp. Sensor Fault (as printed; P17 is the suction sensor in other Activair/Zeno tables).
Part involved: temperature sensor/thermistor.
Likely causes:
- Sensor open/short circuit or disconnected.
On the Activair R290 Indoor (3.2kW wall hung / 5kW floor standing)
The manual says: Suction Temp. Sensor Fault.
Part involved: temperature sensor/thermistor.
Likely causes:
- The temp. sensor is broken or short circuit.
On the Activair Pro (AI) R290 6/12/17kW
The manual says: Suction Temp. Sensor Fault.
Part involved: temperature sensor/thermistor.
Likely causes:
- The temp. sensor is broken or short circuit.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
What you can check
- Note the exact code shown on the controller (a photo helps) and report it to your installer or the manufacturer's service line.
- Check the heat pump's supply breaker/isolator at the consumer unit is on (do not open any casing).
What the engineer will check
On the Activair Commercial R290 50kW (FG9550)
- Check and replace the system 1 suction temperature sensor.
Who to ask for: heat pump controls / electrical.
Certification: Competent heat pump engineer; electrical competence for work inside the unit.
On the Activair High Temperature R290 (5/9/15/22kW)
- Check the connection.
- Measure the resistance of sensor.
- if lower than 100 ohm or higher than 500 kohm, replace it.
Who to ask for: heat pump controls / electrical.
Certification: Competent heat pump engineer; electrical competence for work inside the unit.
On the Activair R290 Indoor (3.2kW wall hung / 5kW floor standing)
- Check or change the temp. sensor.
Who to ask for: heat pump controls / electrical.
Certification: Competent heat pump engineer; electrical competence for work inside the unit.
On the Activair Pro (AI) R290 6/12/17kW
- Check or change the temp. sensor.
Who to ask for: heat pump controls / electrical.
Certification: Competent heat pump engineer; electrical competence for work inside the unit.
What you might notice
Sources
- Trianco Activair Commercial High Temperature Air Source Heat Pump (R290 50kW FG9550) - Installation Operation and Service Manual ↗ · 2024-10 · page 40 · Reviewed 23 September 2026
- Trianco Activair High Temperature Air Source Heat Pump (R290 5/9/15/22kW) - Installation Operation and Service Manual ↗ · November 2024 (PDF regenerated 2026-08) · page 37 · Reviewed 23 September 2026
- Trianco Activair R290 High Temperature Indoor Air Source Heat Pump (3.2kW wall hung) - Installation Operation and Service Manual ↗ · 2026-08 · page 32 · Reviewed 23 September 2026
- Trianco Activair Pro Air Source Heat Pump (R290 6/12/17kW) - Installation Operation and Service Manual ↗ · 06/2026 · page 39 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026