2.0 Medium

Worcester Bosch 2.0 Fault Code

Also written as 20 — same fault.

The Worcester Bosch 2.0 fault code means: your boiler is currently in a manual testing mode used by engineers to check its performance rather than a standard fault, meaning it is not operating normally for your home heating.. It appears on 3 Worcester Bosch models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Service function used to set operating mode (0. = Normal mode, 1. = min. rated heat output, 2. = max. rated heat output)
Typical repair cost £80-120 (including labour)

DIY fix possible

Locate the reset or 'service' button on your boiler control panelPress and hold the service button for several seconds until the display reverts from the number to a standard standby symbolOnce the display shows a normal status, turn on a hot water tap to ensure the boiler returns to standard operation

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 2.0 fault code

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

Source

Worcester Bosch 2.0 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