Baxi Combi 130 HE Fault codes & diagnostics

41 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 30 kW 2005-2010 Discontinued
GC Number 47-075-04

Replaced by: Baxi Duo-tec Combi HE

Download the Baxi Combi 130 HE manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

This boiler uses LED flash patterns

Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
37 High 3 Medium 1 Low
Just want the most common Baxi Combi 130 HE faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 41 documented codes

Tap any card for details

LED / flash-pattern codes
A neon flashing

Your boiler is struggling to light or cannot keep the flame burning, which has caused it to shut down for safety.

High DIY-safe £100-£250

What to check first

  1. Check that your gas pre-payment meter (if applicable) has credit.
  2. Verify that other gas appliances, like a cooker, are working to ensure gas supply exists.
  3. Reset the boiler by turning the selector switch to 'R' for at least five seconds and then back to the desire setting.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Flame Sensing Lead
Full explanation for A neon flashing
B neon flashing

Your boiler has stopped working because water is not moving through the system properly or there is not enough water inside it.

High DIY-safe £180-350

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.
  2. If the pressure is too low, use the filling loop to top it up.
  3. Ensure all radiator valves and isolation valves are fully open.

Parts commonly replaced

  • Circulating Pump
  • Primary Water Pressure Switch
  • Flow Temperature Sensor
Full explanation for B neon flashing
B, C, D, E & F neons flashing

Your boiler has detected a problem with how it moves air and exhaust gases through the system, causing it to shut down for safety.

High Engineer only £120-£240

Parts commonly replaced

  • Air Pressure Switch
  • Venturi Tube
  • Fan
Full explanation for B, C, D, E & F neons flashing
C neon flashing

Your boiler has detected that water isn't moving through the internal pipes effectively, which prevents it from heating up safely.

High DIY-safe £120-280

What to check first

  1. Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge
  2. Open any radiator valves that are turned off to ensure water can flow
  3. Ensure the main stop tap and any isolation valves under the boiler are fully open

Parts commonly replaced

  • Pump
  • Primary Flow Switch
  • Diaphragm

Related codes

Full explanation for C neon flashing
D neon flashing

Your boiler has become too hot and has shut down as a safety precaution to prevent damage.

High DIY-safe £100-£250

What to check first

  1. Turn the boiler off and allow it to cool down for 30 minutes
  2. Ensure all radiator valves are fully open to allow water to flow
  3. Turn the selector switch to the reset position for five seconds and then back to the menu

Parts commonly replaced

  • Overheat Thermostat
  • Central Heating Pump
  • Flue Thermostat
Full explanation for D neon flashing
E neon flashing

Your boiler has detected a problem with one of its internal temperature sensors, meaning it cannot accurately monitor the water temperature and has stopped working as a safety precaution.

High Engineer only £90-160

Parts commonly replaced

  • Central Heating NTC Sensor
  • Domestic Hot Water NTC Sensor
Full explanation for E neon flashing
Lights Flash Flash On

Your boiler has stopped working because the internal fan can't spin properly to clear waste gases.

High Engineer only £150-£350

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • Wiring harness
Full explanation for Lights Flash Flash On
Lights Flash Off On

Your boiler has switched itself off because it has become too hot internally, usually due to a lack of water flow or a circulation error.

High DIY-safe £120-£350

What to check first

  1. Check that your radiator valves are open to allow water to flow.
  2. Check the boiler pressure gauge and top it up to 1.5 bar if it is too low.
  3. Allow the boiler to cool down for 20 minutes and then press the reset button.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Heat Exchanger
Full explanation for Lights Flash Off On
Mains LED flashing

Your boiler is failing to communicate with its control panel, which means it cannot receive instructions to switch on for heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Control PCB
  • Interface PCB
  • Wiring harness
Full explanation for Mains LED flashing
Digital codes
24

Your boiler has stopped working because it cannot light the flame or the internal drainage pipe is backed up with water.

High DIY-safe £90-280

What to check first

  1. Check if your shared external white drainage pipe is frozen or blocked.
  2. If frozen, pour warm (not boiling) water over the pipe to clear the ice.
  3. Press the reset button once to see if the boiler restarts.

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Gas valve
  • Condensate trap
Full explanation for 24
Showing 11–20 of 41
25

Your boiler has shut down because a safety sensor has detected that the system is starting to overheat.

High DIY-safe £120-£350

What to check first

  1. Ensure all radiator valves are fully open
  2. Check that the system water pressure is between 1.0 and 1.5 bar
  3. Switch the selector dial to the reset position for five seconds and release

Parts commonly replaced

  • Safety Thermostat (Overheat Limit)
  • Circulation Pump
  • Main Heat Exchanger (Descaling)
Full explanation for 25
26

Your boiler has stopped working because the fan cannot safely clear exhaust fumes from the system.

High Engineer only £150-£350

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • Venturi tube
Full explanation for 26
27

Your boiler is struggling to circulate water, which is usually caused by the system pressure being too low or a problem with the internal pump.

High DIY-safe £180-350

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1.0 and 1.5 bar.
  2. If the pressure is too low, use the filling loop underneath the boiler to top it up.
  3. Reset the boiler by turning the selector switch to 'R' for five seconds.

Parts commonly replaced

  • Circulating Pump
  • Water Pressure Sensor
  • Expansion Vessel Re-charge

Related codes

Full explanation for 27
28

Your boiler is likely struggling to monitor or control the temperature of your hot water properly due to a faulty internal sensor.

Medium Engineer only £90-160

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Sensor
  • Sensor wiring harness
Full explanation for 28
29

Your boiler has detected an issue with the sensor that monitors the temperature of the water used for your radiators, causing the heating to stop working correctly.

Medium Engineer only £90-160

Parts commonly replaced

  • Central Heating NTC Temperature Sensor
  • Sensor Wiring Harness
Full explanation for 29
Dry-Fire

Your boiler has detected there is not enough water flowing through it to safely heat up, which has caused it to shut down to prevent overheating.

High DIY-safe £120-350

What to check first

  1. Check the pressure gauge on the front of the boiler or under the sink
  2. If the pressure is below 1.0 bar, use the filling loop to top it up to 1.5 bar
  3. Ensure all radiator valves are open and turn the selector switch to reset

Parts commonly replaced

  • Circulation pump
  • Flow switch
  • Pressure sensor
Full explanation for Dry-Fire
E06

Your boiler has lost the ability to accurately measure the temperature of the water it is heating for your taps, so it has stopped providing hot water to ensure safety.

High Engineer only £120-200

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor
  • Wiring harness

Related codes

Full explanation for E06
Flame Failure (Red Light) ON

Your boiler has failed to light the burner and has locked itself out for safety purposes.

High DIY-safe £100-350

What to check first

  1. Check that your gas supply is turned on and that other gas appliances are working.
  2. Press and hold the Reset button for 1 to 3 seconds.
  3. Verify that you have credit on your gas meter if you are on a pay-as-you-go plan.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • PCB (Printed Circuit Board)
  • Flame Sensing Probe
Full explanation for Flame Failure (Red Light) ON
Flow Thermistor

Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, meaning it cannot heat your home or water safely.

High Engineer only £90-160

Parts commonly replaced

  • Flow Thermistor (NTC Sensor)
  • Wiring Harness
  • Main PCB
Full explanation for Flow Thermistor
Showing 21–30 of 41
Ignition Lockout

Your boiler has failed to light the flame and has safely shut down to prevent gas from building up inside the unit.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)
Full explanation for Ignition Lockout
L0

Your boiler has failed to start up or stay lit and has stopped working as a safety precaution.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)
Full explanation for L0
L2

Your boiler has stopped working because it cannot measure the temperature of the water flowing through it, meaning it doesn't know when to turn the heat on or off.

High Engineer only £120-200

Parts commonly replaced

  • NTC Flow Thermistor
  • Wiring harness

Related codes

Full explanation for L2
L3

Your boiler is struggling to accurately measure the temperature of the water returning to it, so it has shut down to prevent potential damage.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness

Related codes

Full explanation for L3
L4

Your boiler's electronic control panel is experiencing a communication error, meaning it cannot properly regulate the heating or hot water functions.

High Engineer only £150-300

Parts commonly replaced

  • Intellistat Control Board
  • Wiring Harness
Full explanation for L4
L5

Your boiler has detected that the internal fan is operating at a temperature higher than it should, causing the system to stop working to protect itself from potential damage.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • PCB
Full explanation for L5
L6

Your boiler's water circulation system has stopped working, meaning it cannot move heat around your home or to your taps.

High Engineer only £180-350

Parts commonly replaced

  • Circulation pump
  • Pump wiring harness
  • Printed Circuit Board (PCB)
Full explanation for L6
L7

Your boiler has detected that it is running without enough water inside, which prevents it from operating safely to protect the system from overheating.

High DIY-safe £80-150

What to check first

  1. Locate the external filling loop, usually two braided hoses connected to the pipework under the boiler.
  2. Open the filling valve slowly until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
  3. Close the valve tightly to prevent the system from over-pressurising.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
  • Expansion vessel
Full explanation for L7
L8

Your boiler has detected that it is running without enough water inside, which prevents it from firing up to provide your heating or hot water.

High DIY-safe £80-120

What to check first

  1. Locate the external filling loop, usually a silver braided hose under the boiler.
  2. Open the valves on the filling loop to allow cold mains water into the boiler.
  3. Monitor the pressure gauge on the front panel until the needle reaches the green zone, typically between 1.0 and 1.5 bar.
  4. Close both valves tightly and restart the boiler.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
  • Expansion vessel
Full explanation for L8
L9

Your boiler has detected that the internal components responsible for clearing exhaust gases are not working correctly, so it has safely shut down to prevent any risk.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)
Full explanation for L9
Showing 31–40 of 41
Ld

Your boiler has detected that the water inside it has become dangerously hot and has shut itself down to prevent damage.

High Engineer only £150-300

Parts commonly replaced

  • NTC Sensor
  • Primary Heat Exchanger
  • Pump
Full explanation for Ld
LE

Your boiler has detected that the ventilation system is getting too hot and has automatically shut itself down to prevent damage.

High Engineer only £150-250

Parts commonly replaced

  • Fan overheat thermostat
  • Flue fan assembly
  • Wiring harness

Related codes

Full explanation for LE
LF

Your boiler is unable to drain away the water it creates during normal operation, so it has shut down to prevent internal flooding.

High Engineer only £90-160

Parts commonly replaced

  • Condensate trap
  • Condensate pipework
  • Siphon
Full explanation for LF
Lh

Your boiler has detected an internal communication error with its control panel, which means it will likely stop heating or providing hot water to prevent unpredictable operation.

High Engineer only £250-400

Parts commonly replaced

  • Display PCB
  • Main Control PCB
  • Wiring harness
Full explanation for Lh
Lockout LED continuously on

Your boiler has stopped working because it cannot light its internal flame, meaning you currently have no heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Spark generator
Full explanation for Lockout LED continuously on
Lt

Your boiler is failing to detect when you turn on a hot tap, so it isn't heating the water for your shower or kitchen faucet.

Medium Engineer only £120-220

Parts commonly replaced

  • DHW Flow Switch
  • Diaphragm assembly
Full explanation for Lt
Mains LED off

Your boiler has completely lost power and is unable to turn on or heat your home.

High Engineer only £100-250

Parts commonly replaced

  • External spur fuse
  • Control PCB
  • Transformer
Full explanation for Mains LED off
Overheat Lockout

Your boiler has switched itself off because it has become too hot to operate safely and requires a manual reset once it has cooled down.

High DIY-safe £100-350

What to check first

  1. Ensure all radiator valves are fully open to allow water to flow.
  2. Wait for the boiler to cool down for at least 30 minutes.
  3. Turn the selector switch to the 'Reset' position and hold for 5 seconds before turning it back to 'On'.

Parts commonly replaced

  • Circulating Pump
  • Overheat Thermostat
  • Main Heat Exchanger
Full explanation for Overheat Lockout
PCB Fault

Your boiler's internal computer brain has detected an electronic error and has stopped working to protect the system.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Wiring Harness
Full explanation for PCB Fault
Return Thermistor

Your boiler has detected a problem with the sensor that monitors the water temperature coming back into the unit, causing it to stop running for safety.

High Engineer only £90-180

Parts commonly replaced

  • Return Thermistor (NTC Sensor)
  • Wiring Harness
  • Main PCB
Full explanation for Return Thermistor
Showing 41–41 of 41
Wiring Harness

Your boiler has stopped working because of a loose connection or a fault in the internal electrical wiring between the main control board and the internal components.

High Engineer only £120-250

Parts commonly replaced

  • Main Wiring Harness
  • 8-way PCB Connector
  • Printed Circuit Board (PCB)
Full explanation for Wiring Harness
Status & diagnostic codes

3 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

DHW FLOW SWITCH Diagnostic Your boiler thinks you have a hot water tap turned on even when they are all closed, which may prevent your central heating from working properly. FAN Diagnostic Your boiler has detected an internal electrical communication error or a potential component failure preventing the fan from starting safely. OF Status Your boiler is currently set to a state where the central heating function has been deactivated.