Trane Error Code CoF: Continuous fan demand (Furnace)

Updated October 16, 2026 · by Aurora Star Tech Inc.

Trane error code CoF on a furnace means: Continuous fan demand. It is also called Trane diagnostic code CoF.

Low severityFurnaceTrane S8V2 · Trane S8B1 · Trane S8X1 · Trane S8X2 · Trane S9V2

Homeowner? What Trane code CoF means for you

Usually minor Your furnace is reporting: Continuous fan demand. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
Make sure the furnace front door or panel is closed properly; many furnaces will not run with the door switch open.
Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
Check that the gas valve next to the furnace is open (handle in line with the pipe). Do not force it.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Trane error code CoF mean?

Display for a continuous-fan call (G only). Also read on a communicating system when the furnace runs the blower for cooling or heat pump operation.

Applies to: S8V2, S8B1, S8X1, S8X2 and S9V2

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Trane models that use code CoF

Show all 44 models

S8B1A026M2PSAB S8B1A040M3PSAB S8B1B040M2PSAB S8B1B060M3PSAB S8B1B060M4PSAB S8B1B080M4PSAB S8B1C080M5PSAB S8B1C100M5PSAB S8B1D120M5PSAB S8V2A040M3PCB S8V2A040M3PD S8V2B060M4PCB S8V2B060M4PD S8V2B080M4PCB S8V2B080M4PD S8V2C080M5PCB S8V2C080M5PD S8V2C100M5PCB S8V2C100M5PD S8V2D120M5PCB S8V2D120M5PD S8X1A026M2PSAB S8X1A040M3PSAB S8X1B040M2PSAB S8X1B060M3PSAB S8X1B060M4PSAB S8X1B080M4PSAB S8X1C080M5PSAB S8X1C100M5PSAB S8X1D120M5PSAB S8X2A040M3PSAB S8X2B060M3PSAB S8X2B060M4PSAB S8X2B080M4PSAB S8X2C080M5PSAB S8X2C100M5PSAB S8X2D120M5PSAB S9V2B040U3VSAC S9V2B060U3VSAC S9V2B080D4VSAC S9V2B080U4VSAC S9V2C100D4VSAC S9V2C100U4VSAC S9V2D120U5VSAC

Other Trane Furnace codes

Code	Meaning
---	Faults cleared confirmation
ARF	Calculated airflow readout (cfm x 10)
Both LEDs flashing together	Bluetooth pairing in progress
CL1	Cooling, stage 1
CL2	Cooling, stage 2
CP1	Cooling / heat pump, stage 1 (single-stage models)
CP2	Cooling / heat pump, stage 2
Cr	Control code release number
dFt	Outdoor defrost demand
E01	Furnace control internal failure
E04	Open limit (main limit, rollout or reverse airflow)
E05	Flame sensed when no flame should be present

All Trane Furnace error codes →

Trane code CoF: homeowner questions

What does Trane code CoF mean?

Continuous fan demand. Display for a continuous-fan call (G only). Also read on a communicating system when the furnace runs the blower for cooling or heat pump operation.

Is it safe to keep using my furnace with code CoF?

Usually yes. Code CoF is normally minor, but if it keeps coming back have it checked.

Can I reset Trane code CoF myself?

You can try one reset (power off for 30 seconds, then on). If Trane code CoF comes back, the cause is still there and a licensed technician should check it.

Who can fix Trane code CoF near me?

Aurora Star Tech Inc. repairs Trane furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean

Troubleshooting guides

Blower cycles on and off All brands · Furnace
Blower runs, not enough heat All brands · Furnace
Blowing cold air All brands · Furnace
Board shows "flame sensed with no call for heat" All brands · Furnace
Can't pull oil (distance/lift) All brands · Furnace
CO in flue / poor combustion numbers All brands · Furnace
Cold air blast at start / blower never stops All brands · Furnace
Combustion gas / odour in house, flu-like symptoms All brands · Furnace
Cycles on limit (not lockout) All brands · Furnace
Does not start All brands · Furnace
Flame burns a few seconds then out All brands · Furnace
Flame conditions table All brands · Furnace
Heat exchanger leak All brands · Furnace
High blower-door ACH50 (>3) All brands · Furnace
High fuel consumption All brands · Furnace
High stack temperature All brands · Furnace
High stack temperature / low efficiency All brands · Furnace
Indoor blower runs, outdoor unit dead All brands · Furnace
Limit opens All brands · Furnace
Locks out — oil but no ignition All brands · Furnace
Low CO2 (<8 %) All brands · Furnace
Low draft / blowback All brands · Furnace
Modulating furnace won't modulate All brands · Furnace
Negative house pressure, backdrafting, infiltration All brands · Furnace
No heat All brands · Furnace
No heat All brands · Furnace
No heat (ignition stage) All brands · Furnace
Noisy All brands · Furnace
Noisy registers, drafts, blower overamps/ECM noise, coil freezing All brands · Furnace
Not running / fault code All brands · Furnace
Oil + ignition OK but no flame All brands · Furnace
Oil on floor All brands · Furnace
Pressure switch open / stuck All brands · Furnace
Puff-back / delayed ignition All brands · Furnace
Reduced airflow, hot motor All brands · Furnace
Reduced pressure, smoky shutdowns, lockouts All brands · Furnace
Rollout switch tripped All brands · Furnace
Short cycling All brands · Furnace
Smoke, soot, odour, pulsation All brands · Furnace
Starts but locks out — no oil at nozzle All brands · Furnace
Too little / too much air All brands · Furnace
Unsatisfactory heat (short cycles / uneven / not enough) All brands · Furnace
Water flows with furnace off All brands · Furnace
Read or clear the last 6 faults (L6F menu) Trane · Furnace
Reading and clearing fault history - Trane S-Series IFC Trane · Furnace
Reset the control to factory defaults Trane · Furnace
Run test mode (furnace) Trane · Furnace

Source: Trane S8V2 installation FNR-SVX003A-EN, Figure 73, p.58; Trane S8B1/S8X1/S8X2 installation 18-CE14D1-1A-EN, System Status Menu, p.57; S9V2 installation 18-CE19D1-1B-EN wiring note. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.