Your boiler's computer memory chip is not being recognised or is mismatched, which prevents the system from starting up.

Incorrect code plug detected

What causes this fault?

This fault occurs when the boiler's internal memory chip, which stores the specific settings for your model, fails to communicate with the main control board. The most common reason is that the chip has worked loose, become corrupted by an electrical surge, or was incorrectly installed during a recent repair. Because the boiler no longer knows its own technical specifications, it shuts down as a safety precaution.