Vokera Furnaces Error Codes

01

Furnace fails to ignite; the display shows 01 shortly after a call for heat.

Ignition Failure / No Flame Detected

02

Furnace locks out with code 02; the fan runs but the burner does not light.

Flame Loss During Operation

03

The display shows 03 and the furnace will not start; the fan may not run.

Fan / Air Pressure Fault

04

The furnace shows 04 and shuts down, often after running for a short time.

Overheat / High Limit Thermostat Trip

05

Code 05 is displayed; the furnace does not respond to thermostat demand.

Flow Temperature Sensor Fault

06

The display shows 06; the furnace may run erratically or not at all.

Return Temperature Sensor Fault

07

The furnace shows 07 and will not fire, often after power-up.

Flow Sensor / Thermistor Short Circuit

08

Code 08 appears; the furnace may overheat or shut down unexpectedly.

Return Sensor / Thermistor Short Circuit

09

The furnace displays 09 and will not start, often after a power surge.

EEPROM / PCB Configuration Error

10

Code 10; the furnace does not start, and the fan may run briefly then stop.

Flue Gas Overheat / Flue Thermostat Trip

11

Display shows 11, furnace will not fire, fan may not start.

Fan Speed / Tachometer Fault

12

Code 12, furnace cycles on and off rapidly or fails to modulate correctly.

Flow Temperature Rise Too Fast

13

Furnace shows 13, burner shuts down, may coincide with high system temperature.

Return Temperature Rise Too Fast

20

Code 20, furnace unresponsive to thermostat, no call for heat recognized.

Room Thermostat / External Control Fault

21

Display shows 21, furnace may run at incorrect output or not respond to modulation.

Communication Fault with External Controller

23

Code 23, furnace stops and may show abnormal temperature readings.

Flow Sensor Out of Range / Calibration Error

24

Display shows 24, furnace may lock out or modulate incorrectly.

Return Sensor Out of Range / Calibration Error

27

Code 27, furnace fails to ignite or shuts down shortly after an ignition attempt.

Gas Valve Control Fault

28

Furnace shows 28, ignition attempts may be noisy or irregular.

Ignition Control / Spark Fault

29

Code 29, furnace may light but then shut down, sometimes with a yellowish flame.

Poor Combustion / Low Ionisation Current

31

Display shows 31, furnace may not start or may shut down unexpectedly.

Low System Water Pressure (for hydronic furnace models)

32

Code 32, furnace locks out, pressure gauge may show a high reading.

High System Water Pressure

33

Furnace shows 33, intermittent operation, pressure reading fluctuates.

System Pressure Sensor Fault

40

Code 40, furnace fan runs but the burner does not light, which may indicate an air pressure issue.

Air Pressure Switch Open When It Should Be Closed

41

Display shows 41, furnace may attempt to start with the fan off or at the wrong time.

Air Pressure Switch Closed When It Should Be Open

50

Code 50, furnace unresponsive, display may be blank or frozen.

General PCB / Power Supply Fault

Symptom

Furnace blower runs continuously even when there is no call for heat.

Fan Stuck On / Control Fault

Symptom

Furnace causes vibration or rumbling transmitted through the house.

Mechanical Vibration / Mounting Issue

Symptom

Furnace does not respond to thermostat changes, but the display appears normal.

Control / Thermostat Communication Issue

Symptom

Furnace emits a burning or plastic smell when running.

Overheating Component or Foreign Material on Heat Exchanger

Symptom

Furnace emits a gas smell around the unit, especially at start-up.

Gas Leak or Incomplete Ignition

Symptom

Furnace flue terminal shows signs of black soot or staining.

Sooting / Poor Combustion

Symptom

Furnace frequently locks out and requires a manual reset, with varying codes or no code.

Intermittent Lockout / Unstable Operation

Symptom

Furnace frequently loses pressure and needs topping up.

Chronic System Pressure Loss

Symptom

Furnace is completely dead, with no lights or display, and does not respond to the thermostat.

No Power to Furnace

Symptom

Furnace produces a whistling or high-pitched noise during operation.

Combustion or Airflow Resonance

Symptom

Furnace runs but makes loud banging or booming noises at ignition.

Delayed Ignition / Burner Light-Off Noise

Symptom

Furnace runs but produces no heat to the home (blower runs, but supply air is cool).

Burner Not Firing Under Call for Heat

Symptom

Furnace short cycles (starts and stops frequently) without reaching the set temperature.

Short Cycling / Overheating or Control Issue

Symptom

Furnace starts but shuts down after a few minutes; the house never reaches the set temperature.

Overheat Trip or Poor Circulation

Symptom

Visible water dripping from the flue terminal outside.

Condensate Discharge / Flue Condensation

Symptom

Water leaking from the bottom of the furnace cabinet.

Internal Water Leak