Error code
Worcester Bosch Boiler 104 — Code Meaning
Solar-cylinder T2 sensor lead break with controller Fault 41. FW 100 controller troubleshooting in Greenstar CDi Classic service booklet 6720830033 (2014/08), page 31. These are controller cause numbers paired with Fault 40 or 41, not standalone boiler fault definitions.
Quick answer
104: Solar-cylinder T2 sensor lead break with controller Fault 41
Meaning
Solar-cylinder T2 sensor lead break with controller Fault 41
First safe check
Photograph the full display, including alternating characters and suffixes.
Stop if
The warning remains, the appliance is not operating normally, or the next step requires internal access.
Who to call
Contact a Gas Safe registered engineer qualified for this boiler if the warning remains, the code is not explained in the matching manual, or any internal investigation is required.
Internal diagnosis and repair require a qualified professional. Follow only the model-approved user actions described below. Keep checks outside the casing and use only a manufacturer-approved reset where the manual allows it.
What does this error code mean?
Solar-cylinder T2 sensor lead break with controller Fault 41.
FW 100 controller troubleshooting in Greenstar CDi Classic service booklet 6720830033 (2014/08), page 31. These are controller cause numbers paired with Fault 40 or 41, not standalone boiler fault definitions.
The reported condition does not, by itself, establish which part needs replacement.
Why is this happening?
- The manufacturer describes: solar-cylinder t2 sensor lead break with controller fault 41. The underlying cause requires assessment on the actual model.
Safe next steps
- Photograph the full display, including alternating characters and suffixes.
- Record the full model from accessible paperwork or an external label; do not dismantle the appliance to find it.
- Match the source below to your exact model manual before following any code-specific instructions.
- If the warning persists, the model is uncertain or the next step requires internal access, stop and contact a Gas Safe registered engineer qualified for this boiler.
Can I fix this myself?
NoUse only the external checks described here. The code alone does not justify a parts replacement.
Safety boundary: Do not remove the boiler casing or work on gas, flue components, combustion settings or internal wiring.
What not to do
- Do not remove the boiler casing or work on gas, flue components, combustion settings or internal wiring.
- Do not repeatedly reset an unexplained or returning warning, or buy parts solely from this display.
When to call a heating professional
Contact a Gas Safe registered engineer qualified for this boiler if the warning remains, the code is not explained in the matching manual, or any internal investigation is required.
Safety warning
Do not remove the boiler casing or work on gas, flue components, combustion settings or internal wiring.
Useful hub links
Other Worcester Bosch boiler codes
Worcester Bosch Boiler 110 — Meaning Not Confirmed
Meaning unconfirmed; exact model documentation is required
Worcester Bosch Boiler 200 — Operating Status
Heating mode
Worcester Bosch Boiler 201 — Operating Status
Hot-water mode
Worcester Bosch Boiler 101 — Code Meaning
Collector T1 sensor lead short circuit with controller Fault 40
Relevant guide
Frequently asked questions
Does 104 identify a failed part?+
No. A code describes a reported condition, and the correct model documentation is needed before diagnosis.
Does this apply to every model?+
FW 100 controller troubleshooting in Greenstar CDi Classic service booklet 6720830033 (2014/08), page 31. These are controller cause numbers paired with Fault 40 or 41, not standalone boiler fault definitions.
Sources and review status
Model dependent · Last reviewed 21 September 2026
- Worcester Greenstar CDi Classic service booklet 6720830033, FW 100 table
model manual · UK · checked 21 September 2026
Solar-cylinder T2 sensor lead break with controller Fault 41. FW 100 controller troubleshooting in Greenstar CDi Classic service booklet 6720830033 (2014/08), page 31. These are controller cause numbers paired with Fault 40 or 41, not standalone boiler fault definitions.