Heat pumps · Error codes · Worcester Bosch
T3-failureWorcester Bosch · Greenstore LECP ground source heat pump (System & Combi)
T3-failure on a Worcester Bosch Greenstore LECP ground source heat pump: Failure on sensor T3 hot water
Short answer
On a Worcester Bosch heat pump, T3-failure means: Failure on sensor T3 hot water. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Failure on sensor T3 hot water.
Part involved: T3 hot water sensor.
When it shows: Sensor below 0 C; hot water production terminated.
Likely causes:
- Sensor below 0 C; hot water production terminated.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes.
Manual reset: Automatic.
What you can check
- Read and note the full alarm text and category letter shown on the controller and pass it to your installer.
What the engineer will check
- Diagnose per chapter 21: Sensor below 0 C; hot water production terminated.
Who to ask for: heat pump installer / electrician.
Certification: Electrical work to BS 7671 by competent person.
What you might notice
Sources
- Installation, Commissioning and Servicing Instructions Worcester Greenstore LECP GSHP (System/Combi 6-11 kW) ↗ · 6 720 806 768 (2013/02) · page 61 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026