Furnace shows E06, heating stops, fan may continue to run for a short time.

Safety: Turn off power before removing any covers or wall sensors.

Steps:

• Identify the sensor: The room NTC may be built into the furnace or installed as a remote wall sensor. Locate the small sensor housing and its cable.
• Check wiring: Inspect the cable from the sensor to the Cointra control board for cuts, staples through the wire, or loose terminals. Reseat the connector.
• Check sensor location: Ensure the room sensor is not installed near heat sources, direct sunlight, or behind curtains, which can cause incorrect readings and faults.
• Test or replace sensor: If you have a multimeter, measure resistance and compare to the Cointra NTC chart. Replace the sensor if readings are abnormal.

Professional help: If wiring and sensor are good, the control board may have a defective sensor input and should be diagnosed by a technician.