High Lockout
E00-737 on Worcester Bosch 24/28CDi II RSF

Your boiler's burner has encountered a serious ignition or combustion failure, meaning it cannot safely light to provide heat or hot water.

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

Burner – Propane Aeromatic, Ref. AC 23/05 3585

What causes this fault?

This fault occurs when the boiler attempts to ignite but fails to establish or maintain a stable flame. The most common reasons include a blockage in the burner assembly, a faulty gas valve preventing fuel flow, or worn-out ignition electrodes that can no longer create the required spark.

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.

Find a Gas Safe engineer
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