York Furnace 2 Red Flashes
Soft lockoutShown as: Two red flashes, then a two-second pause, repeating
The pressure switch is closed when it should be open. Before each heat cycle the control checks that the pressure switch contacts are open; if they are already closed it will not allow the ignition sequence to start.
Manual wording: “2 RED FLASHES: This indicates that the pressure switch is closed when it should be open... Check for a faulty pressure switch or miswiring.”
Documented for: TG8S, TG9S, TM9E, TM9X, TM8X, TM9T, TM8T, TM9V, TM8Y, TM9Y
Likely causes, most common first
- Faulty pressure switch stuck closed
- Miswired pressure switch
What you can safely check yourself
- Turn the furnace off at the service switch for a minute and back on once to see whether the code clears
When to call a technician
A stuck-closed pressure switch is a safety interlock failure. It must be tested and replaced by a technician - never jumper or bypass it.
A York furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation Manual - Single Stage PSC Residential Gas Furnaces, TG9S and GG9S Series (95.5% AFUE Multi-position), 1083287-UIM-A-0114 (Johnson Controls Unitary Products (York), TG9S*MP, GG9S*MP single-stage PSC 95.5% AFUE gas furnaces) · checked 2026-08-25
- Installation Manual - Single Stage PSC Residential Gas Furnaces, TG8S*MP / TGLS*MP / GG8S*MP / GGLS*MP (80% AFUE Multi-position / Standard Low NOx), 998491-UIM-B-1013 (Johnson Controls Unitary Products (York), TG8S*MP, TGLS*MP, GG8S*MP, GGLS*MP 80% AFUE single-stage gas furnaces) · checked 2026-08-25
- Installation Manual - Single Stage ECM Residential Gas Furnaces, TM9E Series (95% AFUE Multi-position), 1083163-UIM-A-0214 (Johnson Controls Unitary Products (York), TM9E*MP single-stage ECM 95% AFUE gas furnaces) · checked 2026-08-25