Furnace error code lookup
Pick the brand, type the code — a flash count, a display code like E223, or a status code like 31 — and get the meaning from that manufacturer's own code list, with a link to the full page for the code.
Results appear as you type. Every result links to the full page for that code — causes, what you can check, and when to call someone.
A furnace fault code is not a standard, and several manufacturers publish more than one code list, so the same count can mean different things even within a brand. Each result is labelled with the code system it belongs to; which list applies to your furnace explains how to tell them apart. Not every blink is a fault either — these patterns mean the furnace is running normally.
Before you trust the count
Miscounting flashes is the most common way to land on the wrong page. Reading a furnace fault code covers finding the light, counting the pattern, and telling a repeating code from a heartbeat. If the furnace is doing something a code cannot wait for — gas smell, repeated tripping, scorch marks — go straight to when to stop and call someone.
How this works
The lookup runs entirely in your browser — nothing is sent anywhere. It searches the same 260 code pages that make up this site, each of which cites the manufacturer manual it was written from. The one-line meanings here are summaries; the linked page has the full entry, its causes, and the source it came from.