Heat pumps · Error codes · Worcester Bosch
E2X.T8-failureWorcester Bosch · Greenstore LECP ground source heat pump (System & Combi)
E2X.T8-failure on a Worcester Bosch Greenstore LECP ground source heat pump: Failure on sensor E2X.T8 heat transfer fluid out
Short answer
On a Worcester Bosch heat pump, E2X.T8-failure means: Failure on sensor E2X.T8 heat transfer fluid out. The heat pump keeps running. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Failure on sensor E2X.T8 heat transfer fluid out.
Part involved: T8 heating medium out.
When it shows: Sensor below 0 C; T8 calculated from T9.
Likely causes:
- Sensor below 0 C; T8 calculated from T9.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running.
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; T8 calculated from T9.
Who to ask for: heat pump installer / electrician.
Certification: Electrical work to BS 7671 by competent person.
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