Ducane Furnaces Error Codes

10

LED or display shows code 10; the furnace attempts ignition multiple times then locks out.

Ignition Lockout After Retries

11

Code 11; no response from the furnace when the thermostat calls for heat; LED indicates no previous faults.

No Call for Heat / Idle State

12

Code 12; the blower runs after the heat cycle much longer than normal; occasional limit trips.

Blower On After Power Interruption / Extended Fan-On Time

13

Code 13; limit switch lockout; the furnace will not heat until power is cycled.

Limit Circuit Lockout

14

Code 14; ignition lockout due to failed ignition attempts; requires a manual reset.

Ignition Lockout

31

Code 31; the pressure switch did not close or reopened during operation.

Pressure Switch Fault During Run

32

Code 32; low heat or no heat; the furnace may run at reduced capacity.

Low Heat / Second Stage Fault (Two-Stage Models)

33

Code 33: Limit or rollout switch open; furnace shuts down mid-cycle.

Limit or Rollout Open During Operation

34

Code 34: Ignition proving failure; burners light briefly or not at all.

Ignition Proving Fault

41

Code 41: Blower running slower than expected; poor airflow from registers.

Blower Motor Fault / Low RPM

42

Code 42: Inducer running when it should be off or not responding correctly.

Inducer Motor or Relay Fault

43

Code 43: Low-stage or high-stage pressure switch fault on two-stage Ducane furnace.

Two-Stage Pressure Switch Fault

44

Code 44: Secondary limit or auxiliary limit open on condensing Ducane furnace.

Auxiliary Limit Open

55

Code 55: Control board memory indicates multiple previous faults; intermittent operation.

Multiple Stored Faults / History Code

E0

Control board shows E0, furnace will not start any heating cycle

Control Board Communication Fault

E1

E1 displayed, furnace does not respond to thermostat call for heat

Thermostat Circuit Open or Short

E2

E2 code, inducer motor does not start, no ignition attempt

Inducer Motor or Pressure Switch Start-Up Fault

E3

E3 code, furnace starts inducer but burners never light, then shuts down

Ignition Failure / No Flame Detected

E4

E4 code, furnace lights but shuts off quickly, repeated retries then lockout

Flame Sense Failure / Flame Dropout

E5

E5 code, furnace shuts down on high temperature, blower may run continuously

High Limit Switch Open / Overheat Condition

E6

E6 code, furnace cycles on and off frequently, may not reach set temperature

Rollout or Auxiliary Limit Fault

E7

E7 code; the blower runs continuously even with the thermostat off; no heat.

Stuck Fan Relay or Fan Control Fault

E8

E8 code; the inducer runs but the pressure switch does not prove; the furnace shuts down.

Pressure Switch Open Fault

E9

E9 code; the pressure switch remains closed when it should be open; the furnace will not start.

Pressure Switch Stuck Closed

Symptom

Burning or electrical smell from the furnace during operation.

Overheating Electrical or Dust Burn-Off

Symptom

Furnace blower runs, but air from registers is cold.

No Heat with Blower Operation

Symptom

Furnace frequently trips the household breaker when starting.

Overcurrent / Electrical Short

Symptom

Furnace makes a loud banging or booming noise at startup.

Delayed Ignition / Burner Light-Off Problem

Symptom

Furnace produces a high-pitched whine or screeching noise during operation.

Blower or Inducer Mechanical Noise

Symptom

Furnace runs but house never reaches set temperature; long run times.

Insufficient Heat Output

Symptom

Furnace runs, but some rooms are much colder than others.

Uneven Heating / Duct Distribution Issue

Symptom

Furnace runs, but the carbon monoxide detector alarms.

Combustion / Venting Hazard

Symptom

Furnace short cycles, turning on and off every few minutes.

Short Cycling Due to Overheat or Control Issues

Symptom

Furnace starts, then shuts off within 30 seconds, repeatedly.

Flame Dropout / Safety Trip

Symptom

Furnace vibrates excessively and rattles ductwork when running.

Excessive Vibration / Mechanical Imbalance

Symptom

Furnace will not start at all; no lights or display; blower and inducer off.

No Power to Furnace

Symptom

Rust-colored water or corrosion visible inside the furnace cabinet.

Internal Corrosion from Condensate or Flue Gases

Symptom

Strong gas smell near the furnace, especially at startup.

Gas Leak or Incomplete Ignition

Symptom

Thermostat clicks, but the furnace does not respond; no inducer or blower.

Low-Voltage Control Circuit Failure

Symptom

Water leaking around the base of the furnace or onto the floor during heating.

Condensate Leak (Condensing Furnace)