Medium
321 on Baxi PLATINUM COMPACT 36 COMBI

Your boiler is displaying a general flashing error indicator, which usually means the system needs to be reset or has detected a temporary operational hiccup.

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

Flashing error

From this model's manual
Verified against the Baxi/Baxi Platinum Compact Combi Baxi Platinum Compact Combi Installation installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check the system pressure gauge to ensure it is between 1 and 1.5 bar.Locate the reset button or turn the mode dial to the reset position for a few seconds.Wait to see if the boiler fires up normally after the reset.

Find a Gas Safe engineer
Search the official register →

Avoid the next call-out bill

A cover plan would handle faults like 321: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

All 17 fault codes on the PLATINUM COMPACT 36 COMBI

Seeing a different code? Every code this model can display, in one place.

Related guides you might find useful