Baxi 130 HE (range) Fault codes & diagnostics

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

Combi Natural Gas 30 kW 2006-2010 Discontinued

Replaced by: Baxi Duo-tec Combi HE

This boiler uses indicator light combinations

Note which lights are on, off, or flashing and at what speed. Match the combination to the cards below. Do not reset until you have noted the pattern. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
3 Emergency 57 High 3 Medium 2 Low

All 65 documented codes

Tap any card for details

Flash Flash On

Your boiler has tried to light several times but failed, so it has locked itself for safety.

High DIY-safe £100-350

What to check first

  1. Check that your gas meter is turned on and you have credit.
  2. Check if other gas appliances, like a cooker, are working.
  3. Turn the selector switch to 'Reset' for 5 seconds, then back to your original setting.

Parts commonly replaced

  • Ignition electrodes
  • Gas valve
  • Printed Circuit Board (PCB)

Related codes

Flash Off Flash

Your boiler has detected that the electrical supply wires are connected the wrong way round or there is a serious wiring fault, causing the system to shut down for safety.

Emergency Engineer only £90-180

Parts commonly replaced

  • None - wiring rectification only
  • Printed Circuit Board (if damaged by surge)

Related codes

Flash Off On

Your boiler has detected that it is firing up without enough water inside, which can lead to overheating and potential damage.

High DIY-safe £100-250

What to check first

  1. Check the pressure gauge on the boiler or under the sink; it should be between 1.0 and 1.5 bar.
  2. If the pressure is too low, use the filling loop to top up the system with water.
  3. Ensure all radiator valves and isolation valves under the boiler are fully open.
  4. Reset the boiler to see if the fault clears.

Parts commonly replaced

  • Main Heat Exchanger
  • Overheat Thermostat
  • Circulation Pump
Flash On Flash

Your boiler has detected an internal communication failure between its electronic control board and the main wiring system.

High Engineer only £180-450

Parts commonly replaced

  • PCB
  • LV Wiring Harness
Flash On On

Your boiler has detected a internal electrical failure or a problem with the fan system, meaning it cannot safely clear waste gases and will stay locked out.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Fan Assembly

Related codes

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
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
Lights On Flash On

Your boiler has detected a sensor failure, which means it cannot accurately measure water temperatures and has shut down as a safety precaution.

High Engineer only £90-160

Parts commonly replaced

  • NTC Thermistor
  • Temperature Sensor
  • Wiring Harness
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
On Flash Flash

Your boiler is not receiving enough electrical power from the grid or your home's wiring to operate safely.

High Engineer only £100-350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Wiring
  • Voltage Regulator
Showing 11–20 of 65
On Flash On

Your boiler has detected a fault with its temperature sensors, which means it cannot safely monitor how hot the water is getting and has shut down as a precaution.

High Engineer only £90-180

Parts commonly replaced

  • NTC Thermistor
  • Temperature Sensor
  • Wiring Harness

Related codes

On Off Flash

Your boiler is not receiving the correct electrical signals or power supply required to start up.

High Engineer only £100-£350

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Fuse
  • Wiring Loom
On On Flash

Your boiler has shut down because it has detected that it is getting dangerously hot or there is a serious internal electrical failure.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Overheat Thermostat
  • Pump

Related codes

Red Flame Failure Indicator

Your boiler has stopped working because it cannot light its internal flame or keep it burning.

High Engineer only £120-250

Parts commonly replaced

  • Ignition lead
  • Ignition electrode
  • Gas valve
3 bar or greater

Your boiler's internal water pressure has climbed too high, causing a safety valve to release water to prevent damage inside the unit.

Emergency Engineer only £120-250

Parts commonly replaced

  • Pressure Relief Valve (PRV)
  • Expansion Vessel
  • Filling Loop
Below 1 bar

Your boiler pressure is currently too low, which means it doesn't have enough water inside to circulate heat around your home.

High DIY-safe £70-130

What to check first

  1. Locate the external filling loop, usually two silver flexible hoses with valves attached under the boiler.
  2. Open the valves slowly to allow mains cold water into the system while watching the pressure gauge.
  3. Close the valves firmly once the needle sits in the green zone between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
CH Fault

Your boiler is providing hot water for your taps as normal, but there is a specific issue preventing the radiators from warming up.

Medium DIY-safe £100-£250

What to check first

  1. Check that your room thermostat is turned up higher than the current room temperature.
  2. Verify that your heating programmer or timer is set to 'ON'.
  3. Replace the batteries in your wireless room thermostat if the display is blank.

Parts commonly replaced

  • Diverter Valve Motor
  • Diaphragm
  • External Room Thermostat
DHW Fault

Your boiler has detected a problem with the domestic hot water system, meaning you likely have no hot water but your central heating may still function.

Medium Engineer only £120-£250

Parts commonly replaced

  • DHW Thermistor (NTC Sensor)
  • DHW Flow Switch
  • Internal Wiring Harness
DHW FLOW SWITCH

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.

Medium Engineer only £90-180

Parts commonly replaced

  • DHW Flow Switch
  • Flow Bush
  • Flow Switch Diaphragm
Showing 21–30 of 65
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
E01

Your boiler is failing to light because it cannot detect a flame or is not receiving gas, meaning it has safely shut down to prevent a gas buildup.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
E02

Your boiler has switched itself off because it has become dangerously hot, likely due to a blockage in the water flow or a internal pump failure.

High Engineer only £120-250

Parts commonly replaced

  • Circulating pump
  • Diverter valve
  • Heat exchanger

Related codes

E03

Your boiler has detected that hot gases are not being cleared out properly, so it has safely shut itself down to prevent overheating.

High Engineer only £150-300

Parts commonly replaced

  • Flue limit thermostat
  • Fan assembly
  • Fan wiring harness

Related codes

E04

Your boiler is struggling to detect water moving through the system, which means it cannot safely fire up to give you heating or hot water.

High Engineer only £150-250

Parts commonly replaced

  • Flow switch
  • Central heating pump
  • Pressure gauge

Related codes

E05

Your boiler has lost the ability to accurately measure the temperature of the water circulating through your radiators, so it has shut down to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • NTC flow temperature sensor
  • Wiring harness

Related codes

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

E07

Your boiler is currently unable to read the water temperature returning from your radiators, so it has safely shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness

Related codes

E20

Your boiler's computer is having trouble communicating with itself and has stopped working as a safety precaution.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
E28

Your boiler has detected an internal electronic error that is preventing it from starting up correctly.

High Engineer only £150-£300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
Showing 31–40 of 65
E50

Your boiler is struggling to accurately measure the temperature of the water it is trying to heat, so it has stopped providing hot water to prevent a system malfunction.

High Engineer only £120-200

Parts commonly replaced

  • NTC Temperature Sensor
  • Wiring Harness

Related codes

E60

Your boiler's internal computer has encountered a critical error preventing it from operating correctly.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
E64

Your boiler's main brain is experiencing a technical glitch and cannot process its internal instructions, which means it will stop working until the control system is reset or serviced.

High Engineer only £250-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
FAN

Your boiler has detected an internal electrical communication error or a potential component failure preventing the fan from starting safely.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB
  • Fan Assembly
  • Wiring Harness
Fan Lockout

Your boiler has detected that the internal fan is not spinning correctly, which is preventing the system from clearing out waste gases and starting up safely.

High Engineer only £220-£450

Parts commonly replaced

  • Fan assembly
  • Venturi tube
  • Air pressure switch
  • Main PCB
Fan not running

Your boiler has stopped working because the component responsible for pushing air through the system has failed to start.

High Engineer only £250-450

Parts commonly replaced

  • Fan assembly
  • Control PCB
  • Wiring harness
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
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
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)
L0

Your boiler has failed to ignite and has stopped itself as a safety precaution, meaning you currently do not have heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

Showing 41–50 of 65
L2

Your boiler has stopped working because it is unable to accurately measure the temperature of the water flowing through the system.

High Engineer only £120-220

Parts commonly replaced

  • System flow thermistor
  • Wiring harness

Related codes

L3

Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has purposefully shut down to prevent damage.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC Thermistor
  • Wiring Harness

Related codes

L4

Your boiler's electronic control unit is experiencing a software or communication error and has stopped the heating and hot water to ensure safety.

High Engineer only £250-450

Parts commonly replaced

  • Intellistat PCB
  • Wiring harness

Related codes

L5

Your boiler is struggling to switch between heating your radiators and providing hot water, which means you will likely have no hot water or central heating until it is fixed.

High Engineer only £180-350

Parts commonly replaced

  • Diverter valve actuator
  • Diverter valve cartridge
  • DHW diaphragm
L6

Your boiler is struggling to push water around your radiators and taps, so it has shut down to prevent damage.

High Engineer only £180-350

Parts commonly replaced

  • Central Heating Pump
  • Pump Head
  • Wiring Connector

Related codes

L7

Your boiler has detected that hot water cannot flow through it properly, so it has shut down to prevent damage to its internal parts.

High Engineer only £150-300

Parts commonly replaced

  • Diverter valve
  • Flow switch
  • Central heating pump
L8

Your boiler has detected that water is not circulating properly around your heating system, so it has safely shut down to prevent damage.

High Engineer only £150-350

Parts commonly replaced

  • Central Heating Pump
  • System Filter
  • Diverter Valve
L9

Your boiler has detected an issue with the internal ventilation system that pushes waste gases outside, so it has purposefully shut down to keep your home safe.

High Engineer only £180-350

Parts commonly replaced

  • Fan assembly
  • Wiring harness
  • Printed Circuit Board (PCB)
Ld

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

High Engineer only £150-300

Parts commonly replaced

  • NTC sensor
  • Central heating pump
  • Heat exchanger
LE

Your boiler has detected that a safety component is getting too hot, so it has shut itself down to prevent damage.

High Engineer only £150-250

Parts commonly replaced

  • Overheat thermostat
  • Fan assembly
  • Wiring harness
Showing 51–60 of 65
LF

Your boiler is struggling to drain away the water it creates during normal operation, which is stopping it from working properly.

High Engineer only £90-160

Parts commonly replaced

  • Condensate trap
  • Condensate pipework
  • Siphon
Lh

Your boiler's electronic control panel is experiencing a communication error, which has caused the system to stop operating until it is reset or repaired.

High Engineer only £150-300

Parts commonly replaced

  • Display PCB
  • Wiring harness
Live & Neutral Reversed

Your boiler has detected that the electrical wires providing its power have been connected the wrong way around, which is a safety risk.

Emergency Engineer only £80-160

Parts commonly replaced

  • External wiring
  • Fused spur unit
  • Printed Circuit Board (PCB) if damaged by surge
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
Lockout will not reset

Your boiler is preventing itself from restarting because it still thinks it is dangerously hot or has run without water.

High Engineer only £150-300

Parts commonly replaced

  • NTC Sensor
  • Pressure Switch
  • Printed Circuit Board (PCB)
Low Electrical Supply

Your boiler is not receiving enough electricity from the mains supply to operate safely and has shut down as a precaution.

High Engineer only £100-350

Parts commonly replaced

  • Main PCB
  • External Voltage Regulator
Lt

Your boiler is failing to detect that you have turned on a hot tap, so it is not heating the water for your shower or kitchen faucet.

High Engineer only £150-250

Parts commonly replaced

  • DHW Flow switch
  • Diaphragm assembly
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
OF

Your boiler is currently set to a state where the central heating function has been deactivated.

Low DIY-safe

What to check first

  1. Check the control panel on the front of the boiler to ensure the heating mode is set to 'On' or 'Auto'
  2. Verify that your external room thermostat or wall-mounted timer is set to a temperature higher than the current room temperature
  3. Ensure the central heating dial on the boiler control panel is turned up to a mid-to-high setting
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
Showing 61–65 of 65
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
Pressure Gauge below 1 bar

Your boiler has lost water pressure and needs a top-up to help it start working again.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver braided hose with two small valves) underneath the boiler.
  2. Open both valves slowly until you hear water entering the system and watch the pressure gauge needle rise.
  3. Close both valves tightly once the gauge reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Expansion vessel
Pressure Gauge exceeds 3 bar

Your boiler has too much water pressure, causing the safety valve to release water to prevent damage.

High DIY-safe £100-220

What to check first

  1. Check that the filling loop valves are tightly closed
  2. Bleed water from a radiator using a bleed key to reduce the system pressure
  3. Monitor the pressure gauge to ensure it returns to between 1.0 and 1.5 bar
  4. Press the reset button if the fault code persists

Parts commonly replaced

  • Expansion Vessel
  • Pressure Relief Valve (PRV)
  • Filling Loop
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
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)