How much does it cost to fix Worcester Bosch error code 5-A1?

Typical repair cost for the Worcester Bosch 5-A1 fault is £120-350 including labour.

5-A1 High

Worcester Bosch 5-A1 Fault Code

Q: What does the Worcester Bosch 5-A1 fault code mean?

Your boiler has detected that the water temperature has exceeded the maximum safe limit, causing it to shut down to prevent damage.

Also written as 5A1 — same fault.

The Worcester Bosch 5-A1 fault code means: your boiler has detected that the water temperature has exceeded the maximum safe limit, causing it to shut down to prevent damage.. It appears on 1 Worcester Bosch model in our database.

Technical description: Maximum flow temperature: 30...82°C.

Typical repair cost £120-350 (including labour)

DIY fix possible

Check that all radiator valves (TRVs) are turned to the maximum setting.Ensure the boiler pressure is within the green zone (usually 1 to 1.5 bar).Check if the magnetic system filter is blocked or needs cleaning.

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Worcester Bosch models that show the 5-A1 fault code

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

Greenstar 2000 Repair: £120-350

Source

Worcester Bosch 5-A1 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