PP11 on a Trianco heat pump: Syst1: Low Pressure Sensor Fault
Short answer
On a Trianco heat pump, PP11 means: Syst1: Low Pressure 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 · 3 sources
What it means
On the Activair Commercial R290 50kW (FG9550)
The manual says: Syst1: Low Pressure Sensor Fault.
Part involved: refrigerant pressure sensor/transducer.
Likely causes:
- The pressure sensor is open or short circuited.
On the Activair R290 Indoor (3.2kW wall hung / 5kW floor standing)
The manual says: Pressure Sensor Fault.
Part involved: refrigerant pressure sensor/transducer.
Likely causes:
- The pressure sensor is broken or short circuit.
On the Activair Pro (AI) R290 6/12/17kW
The manual says: Pressure Sensor Fault.
Part involved: refrigerant pressure sensor/transducer.
Likely causes:
- The pressure 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 low pressure sensor.
Who to ask for: refrigeration / controls.
Certification: F-gas certified engineer if the refrigerant circuit is opened.
On the Activair R290 Indoor (3.2kW wall hung / 5kW floor standing)
- Check or change the pressure sensor or pressure.
Who to ask for: refrigeration / controls.
Certification: F-gas certified engineer if the refrigerant circuit is opened.
On the Activair Pro (AI) R290 6/12/17kW
- Check or change the pressure sensor or pressure.
Who to ask for: refrigeration / controls.
Certification: F-gas certified engineer if the refrigerant circuit is opened.
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 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