Common Boiler Problems

Baxi Boilers

BBS Plumbing and Heating are professional Gas Safe Register installers for Baxi gas boilers and OFTEC registered installers for Baxi oil-fired boilers in the greater London area. We also are fully qualified and experienced to service, upgrade and repair all types of boiler, and carry out repairs to existing hot water and central heating systems.

Baxi Fault codes

Fault codes will be displayed on Baxi boilers to indicate there is an issue. There are different codes to indicate different categories of issues. The most common error codes are explained below:

HE A Range – Combi Platinum / Combi Duo-tec / System Megaflow / Heat only Sola

All fault codes on the HE A range of Baxi boilers are shown as:

Alternative flashing E or E1 and then two additional numbers with or without a letter prefix.

Code A prefixPCB programming code
CauseUsually due to a power supply fluctuation
RemedyResetting the boiler should clear the code
Code 0 prefix or Number without letter prefixNormal operating status codes
CauseSee user guide below
RemedyIn all cases attempt to reset the boiler before calling an service engineer.

Normal operating fault codes an owner may be able to clear

CodePossible Fault Remedial Action
E110Overheating Ensure radiators are bled of air
E119Low water pressureAdd water to the system via filling loop
E125OverheatingEnsure radiators are bled of air
E131Overheating lock outThis may follow a power cut try reset
E133Gas supply fault Check gas is turned on. If prepayment meter check there is credit. If all ok and E133 persists – contact Engineer.
E168PCB lock outThis may follow a power cut try reset

Please Note: When an error code is displayed that is not itemised in the above table, then you will need to call an qualified and experienced Gas Safe Baxi service engineer, such as BBS Plumbing and Heating, and quote the error code displayed.


GA Range – Combi Neta-tec / Combi-tec / System Megaflow Compact

All fault codes on the Baxi GA range of boilers are shown as:

E with additional numbers(s) following.

Code does not have an E prefixNormal operating status code or boiler on/off or temperature etc
CauseSee user guide below. Please note: power cuts can affect the normal boiler operation.
RemedyIn all cases attempt to reset the boiler before calling a service engineer.

Normal operating fault codes an owner may be able to clear

CodePossible Fault Remedial Action
E53Poor combustionCheck flue terminal is not obstructed
E110OverheatingEnsure radiators are bled of air
E117System water pressure HIGHBleed water from radiators
E118System water pressure LOWAdd water via filling loop
E125OverheatingEnsure radiators are bled of air
E133 Gas supply faultCheck gas is turned on. If prepayment meter check there is credit. If all ok and E133 persists – contact Engineer.

Please Note: When an error code is displayed that is not itemised in the above table, then you will need to call an qualified and experienced Gas Safe Baxi service engineer, such as BBS Plumbing and Heating, and quote the error code displayed.


Avanta Range – Combi Exclusive / Combi Plus / System Plus / Heat only

Fault codes on the Avanta range of Baxi boilers are shown as:

E with additional number(s) following.

Code does not have an E prefixNormal operating status code or boiler on/off or temperature etc
CauseSee user guide below. Please note: power cuts can affect the normal boiler operation.
RemedyIn all cases attempt to reset the boiler before calling a service engineer.

Normal operating fault codes an owner may be able to clear

CodePossible Fault Remedial Action
E1OverheatingBleed radiators. Check system water pressure; if low refill via filling loop
E2CirculationBleed radiators. Check system water pressure; if low refill via filling loop
E4Ignition failureEnsure gas supply is turned on. If meter is prepayment ensure there is credit
E7Poor circulationBleed radiators. Check system water pressure – if low refill via filling loop

Please Note: When an error code is displayed that is not itemised in the above table, then you will need to call an qualified and experienced Gas Safe Baxi service engineer, such as BBS Plumbing and Heating, and quote the error code displayed.

Error code E168

There are SIX Baxi boilers that could report an E168 error:

Duo-tec Combi HE Duo-tec Combi HE A

Megaflo System HE Megaflo System HE A

Platinum Combi HE BPlatinum Combi HE A

Error code E168 usually reports on one of four problem areas.

The first two problems listed below are the most common:

The boiler has been reporting other codes previously

Other error codes will have been displayed before code E168. The boiler will have detected a fault and displayed the error code associated with the problem. The boiler will then have been reset, either automatically or manually.

Once the boiler starts up again it may not be able to detect the original fault and so will display E168 as a replacement for the previous code.

Codes that can display prior to E168 are:

E20Boiler temperature sensor fault
E28Flue gas temperature sensor fault
E50Domestic Hot Water temperature sensor fault
E110Overheating (O/H) Thermostat operated – check to circulation and connections to O/H T/stat
E119Water pressure switch cut out (low water pressure in boiler and system)
E125Boiler max temperature exceeded – possible circulation fault
E130Flue gas max temperature exceeded – check connections and flue NTC
E131Power has been turned off during E125 or E130 faults. Check cause of E125 and E130
E133Flame not established in time – checks to be made to gas supply – flue system – condensate discharge – spark generator – electrodes – leads and wiring harness connections
E156Under voltage (lower than 195V) has been supplied to boiler
E160Fan system fault

If any of these codes were seen before E168, the faults can be fixed by reference to the above codes.

The mains supply to the boiler has been interrupted or is irregular

The display of an E168 code could mean that the boiler has been experiencing a voltage either above or below the required 230V supply and can be difficult to identify as irregularities may only occur at certain times.

Please Note: The above information is for guidance only. You will need to call an qualified and experienced Gas Safe Baxi service engineer, such as BBS Plumbing and Heating, for further advice.

The remaining two problem areas concern boiler components, which may not be operational, lack electrical connectivity, or the PCB ( printed circuit board) has developed an issue and needs to be replaced.

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