Heat pumps · Error codes · Worcester Bosch
E1x.T1-shortWorcester Bosch · Greenstore LECP ground source heat pump (System & Combi)
E1x.T1-short on a Worcester Bosch Greenstore LECP ground source heat pump: Short circuit on sensor E12.T1, E13.T1... flow
Short answer
On a Worcester Bosch heat pump, E1x.T1-short means: Short circuit on sensor E12.T1, E13.T1... flow. 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: Short circuit on sensor E12.T1, E13.T1... flow.
Part involved: mixed circuit flow sensor.
When it shows: Sensor above 110 C; circuit mixing valve closed.
Likely causes:
- Sensor above 110 C; circuit mixing valve closed.
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 above 110 C; circuit mixing valve closed.
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