York Furnace error codes
21 York furnace codes and problems, each with ranked causes, safe homeowner checks and honest repair costs. Count the flashes or read the code on your control board, then find it below. Legends vary by board revision, so confirm against the label inside your unit's door.
Of these, 20 need a professional repair and 1 is usually safe to check yourself.
| Code | What it means | Severity |
|---|---|---|
| 2 flashes | York furnace 2 flashes means the pressure switch is closed with the inducer off. Causes, safe checks, and $0–$400 repair costs. | Call a pro |
| 3 flashes | York furnace 3 flashes means pressure switch open with inducer on. Causes: blocked vent, clogged condensate, bad switch. Fixes $0–$1,200. | Call a pro |
| 4 flashes | York furnace 4 flashes means an open high-limit switch from restricted airflow or overheating. Causes, safe checks, fixes and $10–$1,500+ costs. | Call a pro |
| 5 flashes | York furnace 5 flashes means flame sensed with the gas valve off. Causes, safe checks, tech diagnosis and repair costs from $0 DIY to $1,200. | Call a pro |
| 6 flashes | York furnace 6 flashes means pressure switch cycle lockout. Causes, safe checks, fixes and repair costs from $0 DIY to $1,200. | Call a pro |
| 7 flashes | York furnace 7 flashes usually means ignition lockout after failed trials. Causes, safe checks, fixes and repair costs from $0 DIY to $1,200+. | Call a pro |
| 9 flashes | York furnace 9 flashes means reversed 115 VAC polarity. Causes, safe checks, and repair costs from $0 DIY to about $250 for an electrician. | Call a pro |
| 10 flashes | York furnace 10 flashes means the gas valve is energized with no call for heat. Gas-safety steps, causes, safe checks, and repair costs. | Call a pro |
| Blower not running | York furnace blower not running? Causes from blower motor to control board, plus DIY checks and repair costs from $0 to $1,500+. | Call a pro |
| Blower won't shut off | York furnace blower runs constantly? Causes include thermostat fan settings, a stuck fan relay or bad limit switch. Fixes and costs from $0 DIY to $1,800. | DIY-friendly |
| Blowing cold air | York furnace blowing cold air? Causes from thermostat fan settings to flame-proving faults, plus fixes and repair costs from $0 DIY to $1,200. | Call a pro |
| Flame sensor problems | York furnace flame sensor problems cause short cycling and ignition lockout. Learn the causes, fixes and repair costs ($80 diagnostic – $800+ with a board). | Call a pro |
| Ignition lockout | York furnace ignition lockout causes include a dirty flame sensor, weak igniter and low gas pressure. See safe checks, fixes and typical repair costs. | Call a pro |
| Keeps shutting off | York furnace keeps shutting off? Flame sensor, limit, pressure switch & flue causes, safe DIY checks, and repair costs from $0 to $1,200. | Call a pro |
| Leaking water | York furnace leaking water? Common causes include clogged condensate drains, cracked traps and flue issues—plus DIY checks and real US repair costs. | Call a pro |
| Loud bang on startup | A loud bang when your York furnace starts usually means delayed ignition or expanding ductwork. Causes, fixes and repair costs explained. | Call a pro |
| Pressure switch stuck open | York furnace pressure switch stuck open: blocked vents, condensate, or a weak inducer. Diagnosis, fixes and $0 DIY to $1,200+ repair costs. | Call a pro |
| Runs constantly but not enough heat | York furnace runs nonstop but won't warm your home? Causes include dirty filters, duct losses, staging faults & heat exchanger problems. Fixes $0 DIY–$3,500+. | Call a pro |
| Short cycling | York furnace short cycling? Causes range from a clogged filter to a failing flame sensor or limit. DIY checks plus repair costs $0-$2,500+. | Call a pro |
| Won't ignite | Why a York furnace won't ignite: bad igniter, flame sensor, gas or pressure issues, plus safe checks, tech diagnosis and repair costs ($0–$1,200+). | Call a pro |
| Won't turn on | York furnace won't turn on? Causes from no power, dead thermostat, blown fuse or bad door switch, plus fixes and repair costs from $0 DIY to $1,100. | Call a pro |
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