Rheem Furnace error codes
13 Rheem 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.
| Code | What it means | Severity |
|---|---|---|
| Blower not running | Rheem furnace blower not running? Causes include door switch, board fuse, blower capacitor, motor and control board — plus safe DIY checks and repair costs. | Call a pro |
| Blowing cold air | Rheem furnace blowing cold air? Common causes like thermostat fan settings, flame sensor failure or limit lockout, plus fixes and repair costs. | Call a pro |
| Clicking but not starting | Rheem furnace clicking but not starting? Causes include a bad igniter, relay, inducer, control board or transformer. Fixes and costs: $0 DIY to $1,200+. | Call a pro |
| Flame sensor problems | Rheem furnace flame sensor problems cause short cycling and lockouts. Common causes, safe homeowner checks, pro cleaning and typical costs of $80–$250. | Call a pro |
| Ignition lockout | Rheem furnace ignition lockout means failed trial-for-ignition after multiple tries. Causes, safe checks, and $0 DIY to about $1,550 repair costs. | Call a pro |
| Keeps shutting off | Rheem furnace keeps shutting off? Common causes include overheating, flame sensor, pressure switch and limit faults — fixes and costs from $0 to $3,500+. | Call a pro |
| Leaking water | Why a Rheem furnace leaks water: clogged condensate drain, failed pump, AC coil pan, venting issues. Safe checks, pro fixes, and costs from $0 to $2,500+. | Call a pro |
| Loud bang on startup | Rheem furnace loud bang on startup usually means delayed ignition or expanding ductwork. Causes, fixes and costs from $0 DIY to $900. | Call a pro |
| Pressure switch stuck open | Rheem furnace pressure switch stuck open: blocked vents, condensate, or a weak inducer, safe checks, and repair costs from $0 to $1,200 or more. | Call a pro |
| Runs constantly but not enough heat | Rheem furnace runs nonstop but the house stays cool? Learn the likely causes, safe homeowner checks, what a tech will test, and typical repair costs. | Call a pro |
| Short cycling | Rheem furnace short cycling? Causes include dirty filters, overheating limits, oversizing and flame-sensor faults — fixes and costs from $0 to $1,800. | Call a pro |
| Won't ignite | Rheem furnace won't ignite? Common causes include a failed hot surface igniter, dirty flame sensor, or ignition lockout — fixes cost $0–$1,200. | Call a pro |
| Won't turn on | Rheem furnace won't turn on? Causes from tripped breakers to failed boards, safe checks you can do, plus honest US repair costs. | Call a pro |
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