Intergas Furnaces Error Codes

Symptom

Boiler/furnace does not start; the display shows code 0, and no ignition attempt is heard.

No Heat Demand / Standby Lockout

1

Furnace attempts to start but locks out with code 1; no flame is established.

Ignition Failure / No Flame Detected

10

The boiler shows Code 10 and will not fire; the fan may not start.

Fan Speed / Tachometer Fault

11

Code 11 is displayed, the boiler locks out, and the issue may be related to gas valve control.

Gas Valve Control / Modulation Error

12

The boiler intermittently shows Code 12; resets may temporarily restore operation.

Low System Water Pressure / Flow Fault

13

Code 13 is displayed, the boiler stops, and the issue may be associated with condensate issues.

Condensate Drain / Siphon Fault

14

The boiler shows Code 14, has no heating output, and the pump may not run.

Pump Fault / No Circulation

15

Code 15 appears, the boiler locks out, and the issue may be related to flue gas temperature.

Flue Gas Temperature Overlimit

16

The boiler shows Code 16, along with erratic behavior of the display and controls.

Control PCB / Internal Error

17

Code 17 is displayed, and the boiler does not respond correctly to external controls.

Communication Fault with Room Thermostat / OpenTherm

18

The boiler shows Code 18, which may be associated with low voltage or power issues.

Mains Supply / Low Voltage Fault

19

Code 19 displayed, boiler fails to start, may be related to the safety chain.

Safety Circuit Open (Limit Switch / Safety Chain Fault)

2

Furnace locks out with code 2 shortly after ignition; the burner shuts down.

Flame Loss During Operation

3

The display shows code 3; the furnace does not start, and the fan may run briefly.

Air Pressure / Fan Fault

4

Boiler shows code 4 and will not fire; this may occur intermittently.

Flow Sensor / NTC Fault (Heating Circuit)

5

The display shows code 5; the boiler shuts down due to high temperature.

Overheat Thermostat / Safety Cut-out Tripped

6

Code 6 is displayed; the boiler will not run and may be accompanied by a very high temperature reading.

Flow Temperature Sensor Overrange / Short Circuit

7

Code 7 is displayed; the boiler does not respond to hot water demand.

DHW Temperature Sensor / NTC Fault

8

Code 8 is displayed; the boiler cycles rapidly or does not modulate correctly.

Flow Sensor / Turbine Fault (DHW Flow Detection)

9

Code 9 appears, the boiler stops, and may show abnormal temperature readings.

Return Temperature Sensor / NTC Fault

Symptom

Boiler display is blank, no lights; the unit is completely dead.

No Power / Dead Appliance

Symptom

Boiler display works, but buttons or controls do not respond properly.

User Interface / Control Panel Fault

Symptom

Boiler fan runs, but the burner does not light, and no error code is displayed.

No Ignition Without Fault Code

Symptom

Boiler frequently locks out during very cold weather; the condensate pipe outside is icy.

Frozen Condensate Pipe

Symptom

Boiler ignites with a loud bang or pop.

Delayed Ignition

Symptom

Boiler loses pressure over time; the user must frequently top up the system.

Chronic Pressure Loss

Symptom

Boiler pressure rises rapidly when heating, and the relief valve discharges water.

Over-Pressurization / Expansion Vessel Failure

Symptom

Boiler runs, but some radiators stay cold or only partially warm.

Poor Circulation / System Balancing Issue

Symptom

Boiler will not start after summer; pump or fan appears stuck.

Seized Components After Long Inactivity

Symptom

Condensate water dripping from flue joints or the boiler casing.

Condensate Leakage from Flue System

Symptom

Furnace frequently cycles on and off, resulting in short burner run times and unstable room temperature.

Short Cycling

Symptom

Furnace is very noisy during operation, with whistling or roaring sounds from the burner area.

Combustion Noise / Burner Resonance

Symptom

Furnace makes loud banging or knocking noises when starting or stopping.

Water Hammer / Thermal Expansion Noise

Symptom

Furnace or boiler casing vibrates excessively, with humming felt through walls.

Mechanical Vibration / Imbalance

Symptom

Furnace runs but radiators or air handlers do not get hot enough; long heat-up times.

Underheating / Insufficient Output

Symptom

Radiators get hot, but domestic hot water temperature fluctuates or is too cold.

Poor DHW Performance

Symptom

Soot or scorch marks around the flue terminal or boiler casing.

Incomplete Combustion / Flue Gas Spillage

Symptom

Strong smell of gas near the Intergas furnace/boiler.

Gas Leak

Symptom

Water leaking from the bottom of the Intergas furnace/boiler casing.

Internal Water Leak