5.0 Low

Worcester Bosch 5.0 Fault Code

Also written as 50 — same fault.

The Worcester Bosch 5.0 fault code means: your boiler is currently set to run at its maximum heating capacity, which is typical during a start-up or testing cycle rather than a permanent fault.. It appears on 5 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: Service Function: Max. heating output

What causes the Worcester Bosch 5.0 fault?

This code appears because a service engineer has manually activated the 'chimney sweep' mode using the boiler's internal settings. It is not actually a fault, but rather a deliberate setting that forces the burner to run at full power so that gas pressure and emissions can be accurately tested. If you see this code and an engineer is not present, the service switch may have been left in the wrong position or bumped accidentally.

Typical repair cost £0-80 (including labour)

DIY fix possible

Locate the service buttons on the control panel.Press and hold the 'Reset' or 'Service' button for a few seconds to exit the test mode.Switch the boiler off and back on at the fused spur switch to reset the software.

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Worcester Bosch models that show the 5.0 fault code

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

Source

Worcester Bosch 5.0 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