1-A7 Medium

Worcester Bosch 1-A7 Fault Code

Also written as 1A7 — same fault.

The Worcester Bosch 1-A7 fault code means: your boiler has detected an issue with a temperature sensor normally used in more complex heating systems, often meaning a sensor is faulty or incorrectly configured.. It appears on 1 Worcester Bosch model 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: Temperature at hydraulic point: This service function will only be available, if service function 2-A1 is activated.

What causes the Worcester Bosch 1-A7 fault?

This fault occurs when the boiler's control system loses communication with a specific temperature sensor used to monitor water flow in larger or multi-zone systems. The most common reason is a physical failure of the sensor's internal components or a loose connection in the wiring harness that links the sensor to the main circuit board.

Typical repair cost £90-180 (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 1-A7 fault code

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

Source

Worcester Bosch 1-A7 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