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2022 Main Boiler Error & Fault Codes


This article covers all the error codes that you may encounter with your Main boiler. We have compiled this guide to be used as a reference for engineers, heating contractors and other service engineers who are looking for error code information during an installation, service call or fault finding session.

If your Main boiler has stopped producing hot water or is showing any of the error codes listed, you can probably solve the problem quickly and easily. The first thing you should do, however, is check that there hasn't been an interruption to either your mains power supply or the control supply for your boiler.

Main boiler error codes are split into two sections. One is general and the other is specific to your model of boiler. Below you'll find easy to follow error code definitions. Error codes that are specific to a particular model, such as the Eco Compact.

General Main Boiler Error Codes


Main boiler error codes sometimes appear on the display when you turn the boiler on to heat up your central heating system. Commonly, a fault will cause the boiler to light up with an error code as soon as it is switched on. The codes that appear are usually quite clearly written so it is easy to tell what the problem is and how to fix it.

General Main error codes or fault codes are helpful to the technicians in finding and resolving the issues with household boilers.

should make a note of the displayed error code"
Fault Code Possible Cause
E168Error code E168 could mean that your boiler has detected a problem but can’t work out exactly what it is;
E20"Central Heating NTC Fault indicate faulty components. You
E28PCB Fault indicate faulty components
E50Hot Water NTC Fault indicate faulty components
E110Safety Thermostat operated – displayed when the primary water pressure is less than 0.5 bar. After repressurising the system the boiler should operate. Your installer will be able to advise you about the method of repressurising.
E119"Water pressure switch not operated – displayed when the primary water pressure is less than 0.5 bar. After repressurising the system the boiler should operate. Your installer will be able to advise you about the method of repressurising"
E33Interruption Of Gas Supply or Flame Failure indicates that the gas supply has been interrupted, ignition has failed or the flame has not been detected. Ensure that the gas supply has not been turned off, and turn the selector switch to the reset position and hold for at least 5 seconds. If the boiler does not relight, or the code is displayed regularly.
E60Fan or fan wiring fault

Main Eco Compact Boiler Error Codes


The error codes below are the error codes that may appear on the display when the boiler stops or when there is a fault with the Eco Compact.

These codes are applicable to all Main Eco Compact Boiler models. Error codes can be displayed in any of three ways, via the EPS, the LED display or via the control panel mounted push button switches or any combination thereof.

The Eco Compact boiler error codes in this table are universal. That means that they should work for all versions of the Eco Compact boilers that support digital diagnostics.

Fault Code Possible Cause
E09Gas valve connection error
E15vGas valve error
E20Central heating negative thermistor coefficient (NTC) sensor error
E28Flue negative thermistor coefficient (NTC) sensor error
E40Central heating return sensor error
E83Communication error
E109Pre-circulation fault
E110Safety thermostat operated
E118Primary system water pressure too low
E125Circulation error
E128Flame error
E130Flue negative thermistor coefficient (NTC) sensor operated
E133Interruption of gas supply or flame error
E135Interruption of gas supply
E154Flow return sensor temperature test
E160Fan or fan wiring error
E270Circulation fault (dry fire)
E321Hot water negative thermistor coefficient (NTC) error
E384False flame
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Table of Contents


  1. General Main
  2. Eco Compact

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