BoilerFaultCodesThe 3 most common faults
Your boiler has shut down because the water inside it has become too hot, usually due to a lack of circulation or a blockage in the system.
Why it happens: This fault occurs when the internal sensors detect that the water is heating up too quickly or has reached a dangerously high temperature. The most common reason is that the water cannot move through the boiler properly, which is often caused by a failed pump, a blockage of sludge in the system, or air trapped within the unit.
Check that your radiator valves are fully open.Ensure the boiler pressure is between 1 and 1.5 bar on the gauge.Reset the boiler by turning the control knob to 'Reset' and then back to 'On'.
Your boiler has lost communication with its internal computer chip, meaning the main control board no longer recognizes the specific model it is supposed to be operating.
Why it happens: This fault occurs when the boiler's main control board loses the vital data connection to its identity chip, effectively 'forgetting' which model it is. The most common reason is a loose or failing Boiler Chip Card (BCC) that has vibrated out of place or suffered a small electrical surge that corrupted its memory.
Full guide for C2Your boiler has encountered a temporary system error and requires a simple manual reset to try and resume normal operation.
Why it happens: 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.
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.
on the Zanussi Ultra System
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Zanussi shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue