High Lockout
H.02 – .03 on Baxi 200 Combi (range)

Your boiler is temporarily confused by its internal software settings and cannot start up correctly.

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

Temporary error- incorrect configuration settings C1/C2.

What causes this fault?

This fault occurs when the boiler's internal computer becomes confused about which specific model it is supposed to be. It is usually caused by a glitch in the software or a communication error between the electronic components after a power surge or a component failure. Because the boiler cannot confirm its own identity and safety parameters, it shuts down as a protective measure.

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.

Find a Gas Safe engineer
Search the official register →

Related guides you might find useful

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →