Heat pumps · Error codes · Worcester Bosch
FILWorcester Bosch · Worcester Bosch, all models
FIL on a Worcester Bosch heat pump: Filter is dirty
Short answer
On a Worcester Bosch heat pump, FIL means: Filter is dirty. 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: Filter is dirty.
Part involved: ventilation filter.
When it shows: Filter is dirty.
Likely causes:
- Ventilation unit filter dirty.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Information only |
| Engineer needed? | Yes |
The heat pump keeps running.
Resetting itself: Clears when cause removed.
Manual reset: CR 10 H manual: if a fault cannot be rectified note fault code and sub-code and contact contractor with ID no.
What you can check
- Read and note the full code (and sub-code) shown on the controller and pass it to your installer.
- Change the ventilation filter and reset the filter timer in the FIL menu as described in the CR 10 H manual.
What the engineer will check
- Change filter; reset filter running time in FIL menu.
Who to ask for: heat pump installer / controls engineer.
Certification: None specific; electrical isolation required before wiring checks.
What you might notice
Sources
- CR 10 H room controller manual (multilingual) ↗ · 6720876740 (2017/08) · page 30 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026