E28 High

Main E28 Fault Code

The Main E28 fault code means: your boiler's computer system is currently reporting that it is not compatible with the specific version of the internal control board installed, meaning it cannot safely operate your heating or hot water.. It appears on 7 Main models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Incorrect PCB Fitted
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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Main models that show the E28 fault code

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

Source

Main E28 fault code information on this page is sourced and cross-checked against the official Main service / installation manuals for each affected model.

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