How much does it cost to fix Worcester Bosch error code Internal Fault?

Typical repair cost for the Worcester Bosch Internal Fault fault is £250-450 including labour.

Internal Fault High

Worcester Bosch Internal Fault Fault Code

Q: What does the Worcester Bosch Internal Fault fault code mean?

Your boiler's electronic brain is failing to communicate correctly, which has caused the system to stop working to avoid potential damage.

Also written as INTERNALFAULT — same fault.

The Worcester Bosch Internal Fault fault code means: your boiler's electronic brain is failing to communicate correctly, which has caused the system to stop working to avoid potential damage.. It appears on 2 Worcester Bosch models in our database.

Technical description: Control board likely wet, damaged, or malfunctioning; or small resistor attached to the multiway connector is missing, loose, or in poor condition.

Typical repair cost £250-450 (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 Internal Fault fault code

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

Source

Worcester Bosch Internal Fault 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