Nibe Boilers Error Codes

E01

Boiler locked out, red fault lamp on, no heating or hot water

Ignition Failure Lockout

E02

Boiler attempts to start but shuts down with overheat alarm, flow temperature very high

Primary Circuit Overheat Trip

E03

Boiler shows flue/venting error, burner stops shortly after ignition attempt

Flue Gas Safety / Ventilation Fault

E04

Boiler displays low water pressure alarm, heating and hot water disabled

Low System Pressure

E05

Boiler shows high pressure alarm, pressure gauge above safe range, safety valve may discharge water

High System Pressure

E06

Boiler displays flow temperature sensor fault, burner does not start or cycles rapidly

Flow Temperature Sensor Failure

E07

Boiler displays return temperature sensor fault, poor modulation or lockout

Return Temperature Sensor Failure

E08

Boiler shows domestic hot water (DHW) sensor error, hot water temperature unstable or disabled

DHW Temperature Sensor Fault

E09

Boiler indicates outdoor sensor fault (for weather-compensated systems), heating curve not followed

Outdoor Temperature Sensor Failure

E10

Boiler shows fan speed or fan feedback error, burner does not ignite

Fan Speed Control / Air Pressure Fault

E11

Boiler displays flame loss during operation, repeated ignition attempts then lockout

Flame Supervision Fault

E12

Boiler shows communication error between main PCB and user interface or between boiler and Nibe accessory module

Internal Communication Fault

E13

Boiler indicates sensor short-circuit or over-temperature on flue gas sensor

Flue Gas Temperature Sensor Fault

E14

Boiler shows condensate fault or blocked condensate drain, unit may shut down

Condensate Drain Blockage

E15

Boiler indicates flow switch or flow sensor error, burner will not start

Insufficient Water Flow / Flow Switch Fault

E16

Boiler shows DHW flow sensor error, no hot water despite demand

DHW Flow Detection Fault

E17

Boiler indicates gas valve or gas modulation fault, no or unstable flame

Gas Valve Control Error

E18

Boiler shows power supply or mains frequency error, intermittent resets

Mains Supply / Power Quality Fault

E19

Boiler indicates sensor fault on heating circuit 2 or mixing circuit (if equipped)

Secondary Circuit Sensor Fault

E20

Boiler shows internal overheat or safety thermostat trip, complete lockout

Manual Reset Safety Thermostat Trip

Symptom

Boiler cycles on and off rapidly without reaching set temperature

Short Cycling

Symptom

Boiler display works but there is no response to heating or hot water demand

Demand Signal Failure

Symptom

Boiler does not start at all, display blank or unresponsive

No Power / Dead Boiler

Symptom

Boiler frequently goes into frost protection mode even when not particularly cold indoors

Incorrect Temperature Sensing / Control Logic

Symptom

Boiler frequently locks out and needs manual reset, with varying error messages

Intermittent Control or Sensor Issues

Symptom

Boiler frequently loses pressure over days or weeks without visible leaks

Chronic Pressure Loss

Symptom

Boiler is very noisy during operation (whining, grinding, or rattling)

Mechanical Noise / Wear

Symptom

Boiler leaking water from underneath the casing

Internal Water Leak

Symptom

Boiler makes loud banging or knocking noises when starting or stopping

Kettling / Hydraulic Shock

Symptom

Boiler or flue emits unusual smells (burning, chemical, or flue gas odour)

Overheating or Combustion Issue

Symptom

Boiler runs but hot water temperature fluctuates or goes cold during shower

Unstable DHW Temperature

Symptom

Boiler runs but radiators stay cold or only lukewarm

Poor Heating Performance

Symptom

Boiler runs continuously and overheats the house even when room thermostat is turned down

Control / Thermostat Fault

Symptom

Boiler’s condensate pipe drips constantly even when boiler is off

Condensate or System Water Passing

Symptom

Radiators upstairs are hot but downstairs are cold

Imbalanced or Sludged Heating Circuit