Fault 41 / 103 Low

Worcester Bosch Fault 41 / 103 Fault Code

Also written as FAULT41103 — same fault.

The Worcester Bosch Fault 41 / 103 fault code means: your boiler has detected an electrical problem with the sensor that measures the temperature at the bottom of your solar hot water cylinder.. It appears on 2 Worcester Bosch models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Temperature sensor T2 at bottom of solar cylinder faulty: Short circuit on the sensor lead (T2).

What causes the Worcester Bosch Fault 41 / 103 fault?

This fault occurs when the electrical signal from the temperature sensor at the base of your solar cylinder is interrupted or distorted. The most common reason is a physical short circuit in the wiring or a total failure of the internal components within the sensor itself, preventing the boiler from accurately monitoring solar heat levels.

Typical repair cost £90-160 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Worcester Bosch models that show the Fault 41 / 103 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch Fault 41 / 103 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026