6 red flashes: Pressure switch cycling lockout — the switch opened 5 times in one heating cycle
Call a technician
The furnace lit, lost its draft proof, tried again — five times. The manual names excessive vent restriction and leaking pressure-switch tubing.
From the table: Red-LED chart — two-stage 96% furnaces — source: Goodman GCEC960803BN Installation Instructions, Troubleshooting Chart, pp. 55-56 (read the document, fetched 2026-10-30). Covers: GMEC96 / GCEC96 and their Amana twins — the current two-stage condensing furnaces with a green/amber/red LED trio on the board.
The pressure switch is the furnace's proof that exhaust is actually leaving. On this code it proved, then un-proved, five times in a single call for heat. Goodman's chart names two causes: excessive venting restriction, and leaking pressure-switch tubing. Read those as "the draft is marginal" — strong enough to start, too weak to hold.
Marginal-draft causes you can see from outside the house: a vent terminal half-buried in snow, a screen clogged with lint or ice, a condensate drain running slowly on a condensing furnace. Inside causes — the tubing, the switch calibration, the inducer itself — need a technician with a manometer.
Call a technician — the safe list:
- Run the basics once: thermostat calling for heat, filter clean, power switch on, blower door seated.
- If the code returns, that is the end of the homeowner list. This fault lives inside the cabinet, and the part it names needs testing with a meter.
Not in the older chart
If your Goodman is an older single-LED unit and you counted 6, recount first: the PG-series chart does not assign 6 flashes a heating fault at all (its 6-flash entry is a cooling-mode compressor delay on packaged units). A heating 6 on an old board usually means two stored patterns ran together, or the board is a different generation than the chart. The door chart is the referee.
The two rules that outrank everything on this page.
1. Smell gas? Stop reading. Leave the house and call your gas utility or 911 from outside. No code is worth diagnosing through a gas smell.
2. Never bypass a safety switch — no jumping a pressure switch, no taping a limit, no propping a rollout. Those switches are the only thing between a furnace fault and a fire or carbon-monoxide problem. This library explains codes; it does not teach repairs inside the cabinet.
One honesty note before the tables: codes change between control boards, sometimes inside the same brand and the same decade. Every table below names the board and the manual it was transcribed from. The chart glued inside your own blower door is the final word for your furnace — if it disagrees with this page, believe the door.