Medium
C0 on Zanussi Ultra System

Your boiler has encountered a temporary system error and requires a simple manual reset to try and resume normal operation.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

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

What the manual says

Manufacturer manual

RESTART BOILER

From this model's manual
Verified against the Zanussi Ultra System installation & service manual, page 50.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the small memory chip that stores the boiler's identity fails to communicate with the main control board. The most common reason is a physical connection failure or a software glitch that causes the boiler to lose its configuration settings, rendering it unable to operate safely.

DIY fix possible

Locate the 'Reset' button on the boiler control panel.Press and hold the button for 3 to 5 seconds.Wait a few minutes to see if the boiler fires up and the error code clears.

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