253 High

Worcester Bosch 253 Fault Code

The Worcester Bosch 253 fault code means: your boiler's internal computer is experiencing a critical error while trying to run its own memory check, causing the system to lock up for safety.. It appears on 5 Worcester Bosch 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: RAM test error
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 253 fault code

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

Source

Worcester Bosch 253 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 31 August 2026