Carrier · Status code
Carrier 59SP6B status code 19.1: InteliSense communications loss
Status code 19.1 means the InteliSense communication link between the furnace control and a connected InteliSense-capable thermostat or accessory is not working. Heating itself continues on the standard 24 V thermostat inputs; the code records that the communicating feature lost its link.
On the control
- Code
- 19
- Minor
- 19.1
- Door LED
- 1 short flashes then 9 long
- Controller
- 59SP6B integrated furnace control with 3-digit LCD display and door LED
- Applies to
- Carrier Performance 96 single-stage (59SP6B)
- Manual
- 59SP6B-01SI REV B
What each minor code says, verbatim
| Display | Manufacturer wording |
|---|---|
| 19.1 | InteliSense™ communications loss |
A code is a condition, not a diagnosis
The code says the communicating link is down, not which end failed. Causes include thermostat or accessory wiring, a thermostat that is not InteliSense-capable, power loss to one device, or a control-communication fault. A furnace without any InteliSense device connected should not normally log 19.1; if it does, the control should be checked against the rating plate program.
Which furnaces this applies to
Documented for Carrier 59SP6B furnaces (all nine sizes) in installation instructions 59SP6B-01SI REV A, edition 06/23. The 59SP6B is InteliSense capable when used with an ecobee for Carrier smart thermostat with InteliSense technology; the code appears on furnaces where that connection exists.
Scope: Carrier 59SP6B Performance 96 single-stage furnaces with the on-board 3-digit display control. Not sure which control you have? Send us the full model number from the rating plate.
Safe things to look at first
- Read the full code on the control display through the door, including any minor digit (for example 33.2), and write it down.
- Look, without touching, for obvious conditions you can report: snow or ice at the vent terminations, water on the floor, a loaded filter, a condensate pump that is full or off.
- Note whether the furnace still heats at all, and how long it runs before the code returns.
- Note whether the thermostat itself shows an error or a loss-of-connection message, and whether the furnace still heats on demand.
Do not
- Do not bypass or jumper the door switch, limit switches, rollout switches or pressure switches.
- Do not open the burner compartment, disconnect tubing, or adjust the gas valve or gas pressure.
- Do not keep cycling power to force the furnace to relight; repeated resets hide the fault and can allow unburned gas to build up after ignition failures. If the code returns, stop and call.
Homeowner-safe checks (look and read only)
- Note the thermostat model and whether it shows a connection error
- Confirm the furnace still heats on demand
When to call a technician
- If the furnace stops heating
- If 19.1 appears with no InteliSense device connected
Also documented on the same controller family: Carrier Performance 97 (59TP7A).
What a technician does
- A technician confirms the thermostat model and its communicating wiring, checks for power at both devices, and verifies the control program number matches the rating plate if the code persists.
Questions people ask
Does code 19.1 stop my furnace from heating?
No. Heating still runs from the standard thermostat connections; 19.1 records that the InteliSense data link is down, which affects the smart features rather than the burner.
I do not have an InteliSense thermostat. Why does 19.1 show?
If no InteliSense device is connected, a persistent 19.1 points at the control or its program. Have the program number on the rating plate compared with the control's stored program.
Seeing code 19 on your Carrier?
Tell us the full code, the model number and whether the furnace still heats on low. BC Wide prioritizes no-heat calls across Greater Vancouver.