High
90 on Worcester Bosch 537i

Your boiler has detected that it is not operating according to its expected energy settings, which typically indicates an issue with the internal electronics or the gas-to-air ratio setup.

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.

What the manual says

Manufacturer manual

Heat output 27.2 kW / Heat input 27.5 kW (RD532i L.P.G) or Heat output 33.4 kW / Heat input 33.8 kW (RD537i L.P.G)

From this model's manual
Verified against the Worcester Bosch 537i installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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