BoilerFaultCodesBaxi 4 flashes green Fault Code
Also written as 4FLASHESGREEN — same fault.
The Baxi 4 flashes green fault code means: your boiler is having trouble sending messages between its internal electronic brains, meaning it cannot start the heating or hot water until the connection is restored.. It appears on 11 Baxi models in our database.
Technical description: Communication fault: Bad connection or wiring fault, Internal communication fault
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like 4 flashes green: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Baxi models that show the 4 flashes green fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi 4 flashes green fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026