Baxi Boilers Error Codes

E01

Boiler will not ignite, display shows E01, no flame symbol, heating and hot water not working

Ignition Lockout / Flame Failure

E02

Boiler locks out with E02, overheats and shuts down, may make kettling noises before stopping

Primary Heat Exchanger Overheat / Safety Thermostat Trip

E03

Boiler shows E03 and will not fire, fan may start briefly then stop

Flue Fan / Air Pressure Switch Fault

E04

Boiler displays E04, no ignition, may attempt to start then lock out

Flame Detection Fault / Ionisation Failure

E05

Boiler shows E05, heating and hot water unavailable, temperature reading may be erratic

Flow Temperature Sensor (NTC) Fault

E06

Boiler displays E06, domestic hot water temperature unstable or not recognised

DHW Temperature Sensor (NTC) Fault

E09

Boiler shows E09 and locks out, no heating or hot water

Gas Valve / Burner Control Fault

E10

Boiler displays E10, pressure gauge may be low or flashing, boiler will not run

Low Water Pressure / System Pressure Fault

E11

Boiler shows E11, often associated with fan or flue issues, no ignition

Air Pressure Switch / Flue Safety Fault

E119

Boiler displays E119, pressure gauge low, boiler will not fire

Low System Pressure Lockout

E12

Boiler intermittently locks out with E12, may relate to sensor or PCB communication issues

Internal Communication / Sensor Circuit Fault

E13

Boiler shows E13, often associated with flue gas temperature or sensor issues

Flue Gas Temperature Sensor Fault / Overtemperature

E133

Boiler shows E133, no ignition, may have tried to light several times, often after gas supply interruption

Ignition Lockout / Gas Supply Fault

E16

Boiler displays E16, often related to return temperature sensing or differential issues

Return Temperature Sensor (NTC) Fault

E160

Boiler displays E160, often associated with fan or PCB fault, no ignition

Fan / PCB Communication Fault

E168

Boiler shows E168, often described as a general PCB or power supply fault, intermittent lockouts

PCB / Power Supply Fault

E193

Boiler displays E193, often related to circulation or pump speed issues

Pump Speed / Flow Detection Fault

E20

Boiler shows E20, often associated with pump or circulation problems

Circulation Fault / Pump Error

E25

Boiler intermittently locks out with E25, often during heating demand, may be accompanied by noisy operation

Primary Circuit Overheat / Flow Restriction

E270

Boiler shows E270, often associated with sensor calibration or configuration issues

Configuration / Sensor Calibration Fault

E28

Boiler shows E28, often related to flue or condensate issues, no ignition

Blocked Condensate / Flue Safety Lockout

E40

Boiler displays E40, often associated with external controls or communication faults

External Control / Bus Communication Error

E50

Boiler shows E50, often related to fan speed or modulation control

Fan Speed Control / Modulation Fault

E53

Boiler intermittently locks out with E53, may relate to gas valve modulation or flame stability

Gas Valve Modulation / Combustion Control Fault

E60

Boiler shows E60, often associated with flue or condensate safety chain

General Flue / Condensate Safety Fault

Symptom

Boiler cycles on and off rapidly, never runs for long, rooms take a long time to heat

Short Cycling / Oversized Boiler or Control Issue

Symptom

Boiler display is blank, no lights or response, but mains power is present at the property

No Power to Boiler / Internal Fuse or PCB Failure

Symptom

Boiler does not fire for hot water unless heating is also on (combi boiler)

DHW Flow Detection / Diverter Valve Fault

Symptom

Boiler does not respond to room thermostat, heating will not come on even though hot water works

External Control / Thermostat Fault

Symptom

Boiler frequently loses pressure without visible leaks, pressure rises when hot then drops when cold

Expansion Vessel Failure / PRV Discharge

Symptom

Boiler frequently trips the electrical circuit breaker or blows the fuse

Electrical Short / Overcurrent

Symptom

Boiler leaking water from underneath the casing or pipe connections

Internal Water Leak

Symptom

Boiler locks out occasionally during very cold weather, external condensate pipe is icy

Frozen Condensate Pipe

Symptom

Boiler makes a loud humming or vibrating noise when firing

Resonance / Fan or Burner Vibration

Symptom

Boiler makes loud banging or knocking noises (kettling) when heating is on

Kettling / Localised Boiling in Heat Exchanger

Symptom

Boiler or flue area smells of gas or combustion fumes when running

Gas Leak / Flue Gas Escape

Symptom

Boiler runs but radiators upstairs are hot while downstairs remain cold (or vice versa)

Partial Circulation / Airlock or Balancing Issue

Symptom

Condensate pipe dripping heavily or gurgling noises from boiler during operation

Condensate Drainage Issue

Symptom

Hot water runs hot then cold or fluctuates in temperature when taps are used

DHW Temperature Instability

Symptom

Radiators not getting hot or only partially warm while boiler appears to run

Poor Circulation / System Balancing Issue