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Baxi Fault Codes
Select a fault code to see its meaning, common causes and how to fix it.
EcoBlue, Duo-tec, Platinum, Megaflo & 600/800 codes
- E0 The E0 code on a Baxi boiler indicates that the control board has detected a problem with one or more of the boiler's… Read more →
- E09 The E09 code on a Baxi boiler signals that the control board has detected a problem with the gas valve connection cable… Read more →
- E1 The E1 code on Baxi, Potterton, and Main boilers signals that the sealed central heating circuit has dropped below its… Read more →
- E10 The E10 fault code on a Baxi boiler points to a problem with the outdoor (external) temperature sensor. This sensor… Read more →
- E100 The E100 code on a Baxi boiler indicates that the boiler's printed circuit board (PCB) has detected an internal clock… Read more →
- E109 The E109 fault code appears on Baxi boilers when the appliance detects poor or insufficient water circulation within… Read more →
- E110 The E110 code means your Baxi boiler's safety thermostat has detected that the primary water temperature has climbed… Read more →
- E111 The E111 fault code on a Baxi boiler indicates that the fan is not running at the expected speed. The fan is a critical… Read more →
- E117 The E117 code appears on Baxi boilers when the water pressure inside the central heating system climbs above… Read more →
- E118 The E118 code appears on Baxi boilers when the central heating system pressure has fallen to 0.5 bar or below — well… Read more →
- E119 The E119 fault code indicates that your boiler's system pressure has dropped below 0.5 bar, which is too low for safe… Read more →
- E12 The E12 code on most Baxi boilers signals a differential water flow switch fault where the switch is stuck in the open… Read more →
- E125 The E125 code tells you that the boiler's PCB has detected a problem with primary water circulation — essentially, it… Read more →
- E127 The E127 code appears on Baxi boilers when the anti-Legionella protection cycle has failed to reach or maintain its… Read more →
- E128 The E128 code appears on Baxi boilers when the appliance has tried to light the burner multiple times — up to 12… Read more →
- E129 The E129 fault code indicates a safety lockout caused by the boiler repeatedly failing to hold a flame during its… Read more →
- E13 The E13 code appears on most current Baxi boiler ranges and indicates a differential water flow switch fault where the… Read more →
- E130 The E130 code means your Baxi boiler has locked out after detecting a problem with the flue NTC (Negative Temperature… Read more →
- E131 The E131 code means your Baxi boiler has detected that the flue gas temperature has climbed above its safe operating… Read more →
- E133 Gas supply fault — the boiler failed to light or lost the flame during ignition and has locked out. Read more →
- E134 The E134 code appears when the boiler's control board signals the gas valve to open and allow gas into the burner, but… Read more →
- E135 The E135 fault code on Baxi boilers indicates an internal gas supply interruption, placing the boiler into a safety… Read more →
- E15 The E15 code on a Baxi boiler signals a permanent lockout caused by a breakdown in the command signal between the… Read more →
- E153 The E153 code appears on Baxi boilers when the control system detects that the reset button has been pressed at an… Read more →
- E154 The E154 code on a Baxi boiler signals that the boiler's internal diagnostics have detected a problem during the flow… Read more →
- E160 The E160 code on a Baxi boiler indicates a fan fault. Specifically, the boiler's control board has detected that the… Read more →
- E161 The E161 fault code on a Baxi boiler indicates that the boiler's control system has detected a problem with the fan —… Read more →
- E162 The E162 code is one of a family of Baxi fan-related faults (E160–E163) and indicates a problem with the boiler's flue… Read more →
- E163 The E163 code appears on Baxi boilers when the domestic hot water (DHW) NTC thermistor sensor develops a fault. The… Read more →
- E164 The E164 fault code on a Baxi boiler signals that the boiler's control system has detected an open or absent signal… Read more →
- E166 The E166 code indicates that your Baxi boiler has shut itself down after detecting a potential overheating condition,… Read more →
- E167 The E167 code on a Baxi boiler signals a fault with the Printed Circuit Board (PCB) — the electronic brain that… Read more →
- E168 The E168 fault code on Baxi boilers signals that the boiler's control board has detected an internal electrical problem… Read more →
- E193 The E193 code appears on Baxi boilers when the pre-circulation check fails at start-up. Before the burner fires, the… Read more →
- E2 The Baxi E2 fault code signals that the boiler has detected insufficient water circulation around the central heating… Read more →
- E20 The E20 fault code on a Baxi boiler indicates that the central heating NTC thermistor has reported a problem. The… Read more →
- E270 The E270 fault code on Baxi boilers signals a circulation problem, commonly described as a 'dry fire' condition. This… Read more →
- E28 The E28 fault code on a Baxi boiler signals a problem detected in the flue circuit — most commonly involving the flue… Read more →
- E3 The E3 fault code on a Baxi boiler indicates a problem with the Printed Circuit Board (PCB) — the electronic control… Read more →
- E317 The E317 code appears when your Baxi boiler's PCB detects that the incoming mains electricity is not operating at the… Read more →
- E321 The E321 code appears on Baxi boilers when the control board detects a problem with the hot water NTC (Negative… Read more →
- E384 The E384 code appears when a Baxi boiler detects what it believes to be an active flame even though the gas valve has… Read more →
- E385 The E385 fault code means your Baxi boiler has detected that the incoming mains voltage has dropped below its safe… Read more →
- E4 The Baxi E4 code means the boiler tried to light the burner but could not confirm a stable flame within its permitted… Read more →
- E40 The E40 code appears on Baxi boilers when the PCB detects a problem with the central heating return NTC (negative… Read more →
- E430 The E430 code relates to Baxi's internal water pressure self-check routine. When E430 appears on its own, the boiler is… Read more →
- E432 The E432 fault code (sometimes shown simply as 432 on the display) indicates that your Baxi boiler has detected a… Read more →
- E433 The E433 fault code on Baxi EcoBlue Combi and System boilers indicates that the boiler's control board has detected a… Read more →
- E50 The E50 fault code on Baxi boilers indicates a problem with the domestic hot water (DHW) NTC (Negative Temperature… Read more →
- E53 The E53 code on a Baxi boiler signals a problem with the flue pathway or combustion exhaust system. The boiler has… Read more →
- E54 The E54 code on a Baxi boiler indicates a fault with the domestic hot water (DHW) NTC thermistor — the small… Read more →
- E55 The E55 code on a Baxi boiler indicates that the boiler's internal electronics have detected a communication failure.… Read more →
- E78 The E78 code means your Baxi boiler has detected a problem with its water pressure sensor — the component responsible… Read more →
- E83 The E83 fault code on a Baxi boiler signals a breakdown in communication between the gas valve and the main printed… Read more →
- E84 The E84 fault code indicates a loss of communication between the boiler's printed circuit board (PCB) and one or more… Read more →
- E85 The E85 code on a Baxi boiler signals a breakdown in communication between the boiler's internal components. The PCB… Read more →
- E86 The E86 code appears on Baxi boilers when one internal component has lost the ability to communicate with another —… Read more →
- E87 The E87 fault code on a Baxi boiler signals an internal communication failure — the boiler's main printed circuit board… Read more →
- E92 The E92 code appears on Baxi boilers when a combustion alarm is triggered during the boiler's automatic… Read more →
Baxi 200 & 400 series codes
- E.00-.04 Baxi boilers display fault codes in two parts — the prefix and a suffix — and **E.00–.04** and **E.04–.00** are two… Read more →
- E.00-.05 The E.00-.05 fault code on Baxi boilers indicates that the return water temperature sensor (an NTC thermistor) has been… Read more →
- E.01-.02 Baxi uses a two-part fault code system where the number before the dash identifies the fault category and the sub-code… Read more →
- E.01-.04 The Baxi E.01–E.04 family covers a range of locking faults — meaning the boiler shuts down completely and will not… Read more →
- E.01-.11 The Baxi E.01–.11 fault code tells you that the boiler's control system has detected the combustion fan running at an… Read more →
- E.01-.12 Baxi's E-series codes are permanent lockout faults — the boiler has shut itself down and will not restart until the… Read more →
- E.01-.17 The Baxi E.01-.17 fault code signals that the boiler has detected either a problem with water circulation or a fault… Read more →
- E.01-.20 The Baxi E.01–E.20 range covers temperature and sensor-related faults that cause the boiler to lock out as a safety… Read more →
- E.02-.00 The E.02-.00 code (also displayed as E02-00 or E02 – .00 on some Baxi models) indicates that your boiler has shut… Read more →
- E.02-.07 The E.02-.07 fault code means your Baxi boiler has detected that the system water pressure has fallen below 0.5 bar —… Read more →
- E.02-.16 The E.02-.16 code is a permanent lockout fault on Baxi boilers, triggered when the on-board Channel Service Unit (CSU)… Read more →
- E.02-.17 The E.02-.17 code indicates a permanent, locking communication breakdown between the boiler's gas valve and its PCB… Read more →
- E.02-.19 The E.02-.19 code is a permanent lockout fault on Baxi boilers indicating that the control board (PCB) has detected a… Read more →
- E.02-.20 The E.02-.20 code appears on Baxi boilers when the control board (PCB) detects that configuration Jumper 2 has been… Read more →
- E.02-.21 The E.02-.21 is a permanent lockout fault on Baxi boilers. The 'E.' prefix tells you straight away that this won't… Read more →
- E.02-.47 The Baxi E.02 – .47 fault code indicates that the boiler's control board has been unable to establish or maintain a… Read more →
- E.02-.48 The E.02-.48 fault code (also displayed as A.02.48 on some Baxi models) indicates that the boiler has failed to… Read more →
- E.04-.00 The E.04-.00 fault code on Baxi boilers signals that the boiler's control board cannot detect or communicate with the… Read more →
- E.04-.01 The E.04-.01 code tells you that the boiler's flow temperature sensor — a small NTC thermistor that monitors how hot… Read more →
- E.04-.02 The E.04-.02 code is a permanent lockout fault on Baxi boilers, indicating that the flow temperature sensor (an NTC… Read more →
- E.04-.03 The E.04-.03 code appears on Baxi boilers when either the flow temperature has climbed above the permitted maximum,… Read more →
- E.04-.04 The E.04 group on Baxi boilers represents permanent lockout faults — the boiler shuts down and will not restart on its… Read more →
- E.04-.05 The Baxi E.04-.04 and E.04-.05 fault codes both indicate a permanent lockout caused by a problem with the flue gas… Read more →
- E.04-.06 The E.04 fault code on Baxi boilers relates to the flue gas temperature sensor and its safety circuit. Because the… Read more →
- E.04-.08 The Baxi E.04–.08 code is a permanent lockout fault, meaning the boiler has shut down and will not restart on its own.… Read more →
- E.04-.10 The Baxi E.04 series flags a permanent safety lockout linked to a problem with the gas valve or gas/air unit. The… Read more →
- E.04-.12 The E.04-.12 code is a permanent safety lockout on Baxi boilers, triggered when the control board detects a flame… Read more →
- E.04-.13 The E.04-.13 code is a permanent lockout fault on Baxi boilers, meaning the boiler has shut itself down completely and… Read more →
- E.04-.17 The E.04-.17 code is a permanent lockout fault on Baxi boilers, triggered when the boiler's control system detects a… Read more →
- H.01-.00 The H.01 – .00 code appears when your Baxi boiler detects a temporary loss of communication between the gas valve and… Read more →
- H.01-.05 On Baxi boilers, H-series codes are 'blocking' faults — the boiler pauses or partially shuts down to protect itself but… Read more →
- H.01-.08 The H.01–.08 code is a temporary self-protection status on Baxi boilers, meaning the boiler has detected that the flow… Read more →
- H.01-.14 H-codes on Baxi boilers are 'blocking' faults rather than permanent lockouts. The boiler pauses to protect itself but… Read more →
- H.01-.18 The H.01-.18 fault code on a Baxi boiler indicates that the boiler has detected absent or inadequate water circulation… Read more →
- H.01-.21 The H.01-.21 code is a temporary fault that appears when your Baxi boiler detects the flow temperature climbing too… Read more →
- H.02-.02 The H.02-.02 code is a temporary blocking fault indicating that the boiler's printed circuit board (PCB) has not… Read more →
- H.02-.03 The Baxi H.02.03 fault code indicates a temporary configuration error on the boiler's printed circuit board (PCB).… Read more →
- H.02-.04 The H.02-.04 fault code on Baxi boilers indicates a parameter error — the boiler's control board has either lost,… Read more →
- H.02-.06 The H.02 fault code on Baxi boilers is a blocking (temporary) fault, meaning the boiler pauses operation to protect… Read more →
- H.03-.00 The H.03-.00 code is a blocking fault on Baxi boilers, meaning the boiler pauses to protect itself but may restart… Read more →
- H.03-.01 The H.03-.01 code is a temporary fault on Baxi boilers indicating that the main control board has lost communication… Read more →
- H.03-.02 The H.03-.02 is a temporary (H-type) blocking fault on Baxi boilers, indicating that the flame supervision circuit… Read more →
Flashing-light patterns (display-less models)
- 1 Green Flash A single green flash on a Baxi boiler is a temperature-related signal. In many cases it simply means the boiler has… Read more →
- 1 Red Flash A single red flash on a Baxi boiler indicates a sensor error, temperature fault, or flow fault. The boiler's PCB has… Read more →
- 2 Green Flashes Two green flashes is not listed as a defined fault code in Baxi's standard LED flash-sequence documentation. The… Read more →
- 2 Red Flashes Two red flashes on a Baxi boiler indicate that the boiler's safety overheat thermostat has been triggered. The boiler… Read more →
- 3 Green Flashes Three green flashes on a Baxi boiler indicate that the boiler has detected a temporary loss of flame during operation… Read more →
- 3 Red Flashes Three red flashes on a Baxi boiler indicate a full ignition lockout. The boiler has attempted to light itself five… Read more →
- 4 Green Flashes On Baxi boilers that use LED flash sequences to communicate status — including models in the EcoBlue and 600 ranges —… Read more →
- 4 Red Flashes Four red flashes on a Baxi boiler indicate a fan fault. The boiler's control system has detected that the fan is not… Read more →
- 5 Green Flashes When your Baxi boiler displays 5 green flashes, it is signalling a parameter error on the PSU (Parameter Storage Unit)… Read more →
- 5 Red Flashes Five red flashes on a Baxi boiler indicate a Parameter Storage Unit (PSU) error — a fault within the boiler's control… Read more →
- 6 Green Flashes Six green flashes on a Baxi boiler indicate a miscellaneous or unspecified error, sometimes linked to a fault within… Read more →
- 6 Red Flashes Six red flashes on a Baxi boiler indicate a miscellaneous or unclassified error — essentially a catch-all lockout that… Read more →