Medium Lockout
Fault 14 / 117 on Worcester Bosch Greenstar CDi Compact

Your boiler is having trouble communicating with an external control or thermostat that isn't compatible with it.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

System configuration: incompatible BUS device. DHW controlled by boiler. IPM control of DHW has no effect.

What causes this fault?

This fault occurs when an external thermostat or control unit is trying to talk to the boiler using a language it doesn't understand. It is usually triggered by the installation of an incompatible third-party smart control or a wiring error that disrupts the communication link between the boiler and the wall programmer. The system stops because it cannot receive clear instructions on when to turn the heating or hot water on.

DIY fix possible

Locate your external thermostat or heating controlsCheck if any new smart home devices or controls were recently installedTry resetting the boiler using the 'Reset' button on the front panel

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Related fault codes

204View →B7View →

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