High
6 flashes on Worcester Bosch Greenstar 35 CDi

Your boiler's internal thermometer is broken, meaning it cannot accurately judge the temperature of the water to heat your radiators.

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

CH flow NTC sensor defective.

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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Related fault codes

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