How much does it cost to fix Worcester Bosch error code F7?

Typical repair cost for the Worcester Bosch F7 fault is £120-£350 including labour.

F7 High

Worcester Bosch F7 Fault Code

Q: What does the Worcester Bosch F7 fault code mean?

Your boiler thinks a flame is still burning even after it has been told to turn off, which is a safety conflict that stops the system from running.

The Worcester Bosch F7 fault code means: your boiler thinks a flame is still burning even after it has been told to turn off, which is a safety conflict that stops the system from running.. It appears on 42 Worcester Bosch models in our database.

Technical description: CH flow sensor fault: CH flow sensor (8000 - 20000 ohms at room temperature), Wiring and connections to sensor.

What causes the Worcester Bosch F7 fault?

This fault occurs when the boiler's internal sensors continue to detect a flame or electrical current even after the gas valve has been closed. The most common cause is a carbon-clogged sensing electrode sending a false signal, but it can also be triggered by a fault in the main control board or a short in the internal wiring. Because it is a safety concern for the boiler to 'see' fire when it shouldn't, the system shuts down completely to prevent damage.

Typical repair cost £120-£350 (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 F7 fault code

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

Source

Worcester Bosch F7 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