1-b7 Low

Worcester Bosch 1-b7 Fault Code

Also written as 1B7 — same fault.

The Worcester Bosch 1-b7 fault code means: your boiler is receiving an incorrect or unusual temperature request for your hot water from the external heating controls.. It appears on 1 Worcester Bosch model 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: DHW set temperature: Setting value of the hot water temperature demanded by the heating controller.

What causes the Worcester Bosch 1-b7 fault?

This fault occurs when your external thermostat or heating app sends a temperature command that the boiler doesn't recognize or can't process. The most common reason is a communication glitch or a software mismatch between your wireless controller and the boiler's internal computer.

Typical repair cost £0-120 (including labour)

DIY fix possible

Check your thermostat or heating app to ensure the hot water temperature is set to a normal level (typically 50-60°C).Turn the boiler off and back on at the main isolation switch to reset the communication between the controller and the boiler.Ensure any smart home batteries in your thermostat are not low, as this can cause communication errors.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Worcester Bosch models that show the 1-b7 fault code

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

Source

Worcester Bosch 1-b7 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