How much does it cost to fix Sime error code 04?

Typical repair cost for the Sime 04 fault is £120-200 including labour.

04 High

Sime 04 Fault Code

Q: What does the Sime 04 fault code mean?

Your boiler has lost the ability to monitor the temperature of your hot water supply, meaning it will likely stop producing hot water until the faulty sensor is replaced.

The Sime 04 fault code means: your boiler has lost the ability to monitor the temperature of your hot water supply, meaning it will likely stop producing hot water until the faulty sensor is replaced.. It appears on 3 Sime models in our database.

Technical description: D.H.W. SENSOR ALARM

Typical repair cost £120-200 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Sime models that show the 04 fault code

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

Source

Sime 04 fault code information on this page is sourced and cross-checked against the official Sime service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026