Updated 2026-06-25

About HVAC Flash Codes

An independent reference that makes furnace fault codes easy to look up — and tells you which checks are safe to do yourself.

HVAC Flash Codes is an independent project by Nikolai Tsyrenov, an indie developer. The site compiles furnace flash and fault codes by brand, explains what each one means, and lists the homeowner-safe checks to try before calling a technician.

Each brand's codes are compiled from that manufacturer's own installation and service documentation and carry a confidence flag reflecting how directly the meaning is stated in the source. Furnaces burn gas, so every page draws a clear line between safe homeowner checks and work that needs a licensed HVAC technician.

For how the codes are researched and what the confidence flags mean, see the methodology.

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