Apr52023
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Boilers are an essential part of our daily lives, providing us with hot water and heating our homes. Baxi boilers are one of the most popular brands in the UK and are known for their reliability and efficiency. However, like any mechanical device, Baxi boilers can encounter problems, and when they do, they display error codes to help diagnose the issue. Understanding these error codes can save you time and money, as you can identify the problem before calling a professional boiler repair service. In this blog post, we will explore the different Baxi boiler error codes and what they mean.

BAXI 200 COMBI / BAXI 400 COMBI Boiler Error/Fault Codes

Error Code Possible Fault
H.01 – .00 Temporary Fault – Temporary loss of communication between the gas valve and boiler board. Fault in air/gas unit. Loose connection to the gas valve.
H.01 – .05 Temporary Fault – Maximum difference between the flow and return temperature exceeded. Non-existent or insufficient circulation. Sensor error.
H.01 – .08 Temporary Fault – Flow temperature increasing too fast in heating mode. Non-existent or insufficient circulation. Sensor error.
H.01 – .14 Temporary Fault – Maximum flow temperature value exceeded. Non-existent or insufficient circulation. Non-existent or insufficient circulation.
H.01 – .18 Temporary Fault – No circulation of water. Non-existent or insufficient circulation. Sensor error.
H.01 – .21 Temporary Fault – Flow temperature increasing too fast in DHW mode. Non-existent or insufficient circulation. Sensor error.
H.02 – .02 Temporary Fault – No input of parameters C1/C2. PCB not configured.
H.02 – .03 Temporary Fault– Incorrect configuration settings C1/C2.
H.02 – .04 Temporary Fault – Parameter error. Incorrect parameters.
H.02 – .06 Temporary Fault – System water pressure. Is a water leak in the boiler causing an emergency? Water leaks on the system.
H.03 -.00 Temporary Fault – Communication error with NTC flue sensor. Sensor not, or badly connected. Bad connection. Sensor fault.
H.03 -.01 Temporary Fault – Communication error with the HMI PCB. HMI is not connected.
H.03 -.02 Temporary Fault – No flame during operation. No ionization current.
E.00 – .04 Permanent Fault – Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection. Sensor fault.
E.00 – .05 Permanent Fault – Return temperature sensor open-circuit. Sensor not or badly connected. Bad connection. Sensor fault.
E.01 – .02 Permanent Fault – Temperature measured by return sensor greater than flow sensor. Bad connection. Sensor fault. Sensor not or badly connected.
E.01 – .04 Permanent Fault – Loss of flame detected 5 times in 24 hours (With burner on). No ionization current.
E.01 – .11 Permanent Fault Requiring Reset – Incorrect fan speed. External draught over the boiler. Defective gas/air unit.
E.01 – .12 Permanent Fault Requiring Reset – Temperature measured by return sensor greater than flow temperature.
E.01 – .17 Permanent Fault Requiring Reset – No circulation. Sensor not or badly connected. Sensor fault.
E.01 – .20 Permanent Fault – Maximum flue gas temperature value reached (>140 Deg C). No circulation. Sensor fault.
E.02 – .00 Permanent Fault – Boiler reset in progress. Reset button has been pressed.
E.02 – .07 No or low system water pressure. Low system pressure (less than 0.5bar) boiler will not function.
E.02 – .16 Permanent Fault – Onboard CSU time-out. Check PCB for damage.
E.02 – .17 Permanent Fault – Permanent loss of communication between the gas valve and boiler PCB. Fault in air/gas unit. Loose connection to the gas valve.
E.02 – .19 Permanent Fault – Jumper 1 changed. Check the position of jumper 1.
E.02 – .20 Permanent Fault – Jumper 2 changed. Check the position of jumper 2.
E.02 – .21 Permanent Fault – Jumper 3 changed. Check the position of jumper 3.
E.02 – .47 Permanent Fault – Connection to external device unsuccessful. Check wiring to external device.
E.02 – .48 Permanent Fault – Configuration to external device unsuccessful. Check pairing to external.
E.04 – .00 Permanent Fault – Gas valve fault. Gas valve not detected.
E.04 – .01 Permanent Fault – Flow temperature sensor short-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .02 Permanent Fault – Flow temperature sensor open-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .03 Permanent Fault – Critical flow temperature reached. Non-existent or insufficient circulation.
E.04 – .04 Permanent Fault – Flue temperature sensor short-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .05 Permanent Fault – Flue temperature sensor open-circuited. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .06 Permanent Fault – Critical flue gas temperature value reached. No circulation. Sensor fault.
E.04 – .08 Permanent Fault – Maximum safe temperature value reached. (Safety thermostat open-circuited). No circulation. Sensor not or badly connected. Bad connection. Sensor fault.
E.04 – .10 Failure to light (could be gas supply issue).
E.04 – .12 Permanent Fault – False flame signal. Short-term fluctuation of the mains. Ionization current presents even though there is no flame. The burner remains very hot (CO2 is too high). Defective gas/air unit.
E.04 – .13 Permanent Fault – Fan rotor blocked. Fan seized. Wiring to fan damaged.
E.04 – .17 Permanent Fault – Problem with the gas valve. Defective gas/air unit.

BAXI 600 HEAT / MAIN ECO COMPACT HEAT Boiler Error/Fault Codes

Error Code Possible Fault
1 flash green Maximum flow temperature exceeded, Flow temperature rise rate too high, Excessive difference between, flow and return temperature
2 flashes green BL terminals on User Interaction, Controller are open circuit
3 flashes green No flame detected during operation
4 flashes green Bad connection or wiring fault, Internal communication fault
5 flashes green Parameter error or faulty PU, Configuration error or PCB fault
6 flashes green Possible fault. Internal fault in combustion control unit
1 flash red Bad connection to flow or return temperature sensor
2 flashes red Over-temperature thermostat on heat exchanger activated, No water flow through heat exchanger, PCB over-temperature condition, Flue fault resulting in recirculation or activation of air pressure switch (if fitted)
3 flashes red No ignition, No flame detected following ignition, False flame signal detected
4 flashes red Fan calibration error, Fan failure
5 flashes red Bad connection to PU, Parameter error or faulty PU
6 flashes red Possible fault. Bad connection or wiring fault, Parameter error

BAXI 600 SYSTEM / BAXI 800 SYSTEM / BAXI 600 LPG Boiler Error/Fault Codes

Error Code Possible Fault
E09 Gas valve connection cable
E15 Gas valve fault
E20 Central heating NTC fault
E28 Flue NTC fault
E40 Central heating return NTC fault
E83 Communication error
E109 Pre-circulation fault
E110 Safety thermostat operated
E118 Primary system water pressure too low
E125 Circulation fault (primary)
E128 Flame failure
E130 Flue NTC operated
E133 Interruption of gas supply or flame failure
E135 Interruption of gas supply (internal error)
E135 Interruption of gas supply (internal error)
E154 Flow/ return sensor temperature test
E160 Fan or fan wiring fault
E270 Circulation fault (Dry fire)
E321 Hot water NTC fault
E384 False flame

BAXI ECOBLUE (COMBI & SYSTEM) Boiler Error/Fault Codes

Error Code Possible Fault
E10 Outdoor Sensor Error
E20 Central Heating Thermistor Sensor Fault
E28 Flue Thermistor Fault
E54 HW Flow Sensor Fault
E78 Water Pressure Sensor Fault
E100 Internal Clock Time Error on PCB
E109 Poor Circulation
110 Overheat
111 Maximum Limit of Flow Temperature
117 Water pressure too high
118 Water pressure too low
119 System Pressure Low (<0.5 bar)
125 Water circulation fault
127 Legionella Protection Temperature not reached
128 Loss of flame during operation
133 Safety time to establish flame exceeded
153 Forced reset unit unlocked
160 Fan Fault
162 Air pressure switch error
164 Heating flow switch error (Ireland) Pressure Sensor Error (UK)
166 Air Pressure Switch Fault
270 Dry Fire
432 Earth connector error
433 Heat exchanger temperature exceeded (greater than 95 degrees)

BAXI ECOBLUE (HEAT) Boiler Error/Fault Codes

Error Code Possible Fault
1 Green flash Boiler temperature reached. No action required.
3 Green flashes Temporary flame loss. Boiler will self reset, if fault continues you will see 3 red flashes.
4 Green flashes Communication error between printed circuit board (PCB) and control. Temporary error, will self reset.
5 Green flashes Parameter error on printed circuit board (PCB). Temporary error, will self reset
6 Green flashes Miscellaneous error. Temporary error, will self reset.
1 Red flash Sensor Error; Sensor Fault, Temperature Fault or Flow Fault
2 Red flashes Boiler overheat tripped
3 Red flashes Ignition fault. Boiler has attempted to light 5 times and failed
4 Red flashes Fan Fault
5 Red flashes Parameter or PSU Error
6 Red flashes Miscellaneous error.

BAXI DUO-TEC /MEGAFLO Boiler Error/Fault Codes

Error Code Possible Fault
E10 Outdoor sensor error
E20 Central Heating Thermistor Senor Fault
E28 Flue Thermistor Fault
E110 Boiler Overheat. Ensure radiators are bled of air
E119 Low water pressure. Add water to the system via the filling loop
E125 Primary Water Circulation Fault. Ensure radiators are bled of air
E131 Flue overheat lock out. This may follow a power cut, try reset
E133 Ignition fault – Check gas is turned on, if prepayment meter check there is credit. If all ok and E133 persists – contact Engineer to visit & investigate
E160/E161 Fan Fault
E164 Fan Fault
E167 PCB Fault

BAXI SOLO (HEAT) Boiler Error/Fault Codes

Error Code Possible Fault
Flash Flash On Fan Fault
Flash Off Flash Incoming Voltage less than 180V
Flash Off On Overheat lockout
Flash On Flash PCB fault
Flash On On PCB fault
Off Off Off No power supply
On Flash Flash No circulation/dry fire
On Flash On Thermistor fault
On Off flash Live and neutral reversed
On Off On Ignition lockout
On Off Flash PCB fault
On Off Flash Low voltage wiring harness fault

BAXI GA RANGE Boiler Error/Fault Codes

Error Code Possible Fault
E4 Ignition failure
E09 Gas valve wiring fault
E10 Outdoor sensor error
E15 Gas valve connection fault
E20 Central heating thermistor sensor fault
E28 Flue thermistor fault
E40 Central heating return thermistor fault
E53 Flue obstruction
E55 Calibration required
E78 Water pressure sensor fault
E92 Combustion test alarm during auto-setting
E109 Poor circulation
E110 Boiler overheat tripped
E117 System pressure high (>2.9 Bar)
E118 System pressure low (< 0.5bar)
E125 Primary water circulation fault
E128 Loss of flame during operation
E129 Loss of flame during calibration
E133 Ignition fault
E135 Internal error
E154 Primary flow fault
E160 Fan fault
E270 Dry fire
E317 Wrong power supply (Hz)
E321 Not water thermistor fault
E384 Flame detected when gas valve off
E385 Low voltage (less than 195v)

BAXI AVANTA RANGE Boiler Error/Fault Codes

Error Code Possible Fault
E0 Temperature sensor fault
E1 Boiler overheat tripped
E2 Poor circulation
E3 PCB fault
E4 Ignition failure
E10 Poor/No circulation
E12 PCB Fault
E13 Heat exchanger thermal fuse tripped
E83/84/85/86/87 Fan fault normally E8

BAXI MAIN ECO COMPACT HEAT Boiler Error/Fault Codes

Error Code Possible Fault
1 Green Flash Boiler temp reached
3 Green Flashes Boiler temp reached.Temporary error, self-reset, if continues will go to 3 red flashes
3 Green Flashes Temporary Flame Loss. Temporary error, self-reset, if continues will go to 3 red flashes
4 Green Flashes Communication error between PCB and Control. Temporary error, self-reset.
5 Green Flashes Parameter Error On PSU/PCB. Temporary error, self-reset.
6 Green Flashes Miscellaneous Error. Temporary error, self-reset.
1 Red Flash Sensor Error; Sensor Fault, Temperature Fault or Flow Fault
2 Red Flashes Boiler overheat tripped
3 Red Flashes Ignition fault. Boiler has attempted to light 5 times and failed
4 Red Flashes Fan Fault
5 Red Flashes Parameter or PSU Error
6 Red Flashes Miscellaneous

If you’re facing challenges with your Baxi boiler or need professional advice, our team of fully qualified local plumbers in London is ready to assist you. We also offer emergency gas boiler repair services. Don’t just take our word for it—check out our customer reviews for peace of mind or contact us directly to talk about your requirements!