High
2 lights flashing fast on Worcester Bosch 28 RSF

Your boiler has detected an internal fault preventing it from lighting, most likely caused by a failed safety sensor or a malfunction in the ignition sequence.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

FAIL POINT K or L

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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