Error code

Trane furnace error code 3 Flashes

Snap a photo — see what it is, how urgent, who to call.

One photo of the problem. fixRAgent reads it and gives you a Triage Profile.

Triage a photo now

No sign-up.

Is 3 Flashes on a Trane furnace an emergency?

Treat it as urgent — deal with it today. If you smell gas, do not touch switches or try to relight anything: leave, and call the gas utility or 911 from outside.

Take the photo. We’ll tell you what it is.

Managing this for someone else? Managers: set it up for your buildings →

Managing this for someone else? There is a version of this for whole portfolios.

Managers: set it up for your buildings →

What 3 Flashes means

“Draft Pressure Error”

— Trane, Trane Installer's Guide 18-CD29D1-14-EN, Integrated Furnace Control error flash codes. Codes vary by model: check your furnace’s own manual.

Where 3 Flashes fits

In plain words, 3 Flashes is about venting — the draft or pressure switch did not prove that combustion gases are being pushed out.

Next to 3 Flashes in Trane’s table: 2 Flashes (System Lockout (Retries or Recycles exceeded)) and 4 Flashes (Open High Limit Device).

What to try first

  • Check the vent and intake pipes outside are not blocked (snow, nests, debris); if it continues, call an HVAC technician.

Safety: If you smell gas, do not touch switches or try to relight anything: leave, and call the gas utility or 911 from outside.

How urgent is it?

At least TODAY. fixRAgent treats this code as needing attention today. It points at water where it should not be, overheating, a combustion or ignition safety shutdown, food that may be warming, or a wiring problem. This is fixRAgent’s reading, not the manufacturer’s. A photo can raise it — water near wiring, scorch marks, a gas smell — but a code never lowers what the photo shows.

Who to call

HVAC technician. Have the model and serial numbers from the label ready — a photo of the label works.

Recalls and manuals

Check whether your model is under a safety recall on the U.S. Consumer Product Safety Commission’s site: cpsc.gov/Recalls. Your owner’s manual is on Trane’s support site; search it with the model number from the label.