BoilerFaultCodesWorcester Bosch 2.6 Fault Code
Also written as 26 — same fault.
The Worcester Bosch 2.6 fault code means: your boiler is struggling to maintain a consistent temperature because the difference between the target heat set on your programmer and the actual water temperature is too large.. It appears on 5 Worcester Bosch models in our database.
Technical description: Service Function: Switching difference
What causes the Worcester Bosch 2.6 fault?
This code appears when the boiler has been manually or accidentally switched into a specific service mode that adjustments the burner's firing behavior. It is usually triggered by someone interacting with the internal settings or the control dials in a specific sequence, rather than a mechanical component failing. While in this mode, the boiler pauses its normal operation to allow an engineer to test the temperature gaps between the flow and return pipes.
DIY fix possible
Turn the temperature control dials fully counter-clockwise and then back to your desired settingPress and hold the 'Reset' button for five secondsSwitch the main power supply to the boiler off and back on again after 30 seconds
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Gas Safe Register →Worcester Bosch models that show the 2.6 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 2.6 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