Baxi Suprima 80 Fault codes & diagnostics

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

Regular Natural Gas 23.4 kW 1995-2010 Discontinued
GC Number 41-607-80

Replaced by: Promax SL

Download the Baxi Suprima 80 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.
14 High 2 Medium 3 Low
Just want the most common Baxi Suprima 80 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 19 documented codes

Tap any card for details

LED / flash-pattern codes
1 red flash

Your boiler has detected that it is getting too hot or that water isn't moving through the system correctly, causing it to shut down for safety.

High DIY-safe £120-250

What to check first

  1. Check that all radiator valves are open
  2. Ensure the system pressure is between 1 and 1.5 bar
  3. Press the reset button once the boiler has cooled down

Parts commonly replaced

  • Temperature thermistor (NTC sensor)
  • Circulation pump
  • Overheat thermostat

Related codes

Full explanation for 1 red flash
2 red flashes

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

High DIY-safe £100-280

What to check first

  1. Wait for the boiler to cool down completely (at least 20-30 minutes).
  2. Ensure all radiator valves are open and there is no air trapped in the system.
  3. Press the 'Reset' button on the front control panel to restart the unit.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Thermistor (NTC Sensor)

Related codes

Full explanation for 2 red flashes
3 green flashes

Your boiler is struggling to keep its burner lit and is trying to restart itself automatically.

Medium Engineer only £120-£350

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • PCB (Control board)

Related codes

Full explanation for 3 green flashes
3 red flashes

Your boiler is struggling to light its flame after several attempts, which has caused it to shut down for safety.

High DIY-safe £120-350

What to check first

  1. Check if other gas appliances, like a hob, are working to ensure gas is reaching the property
  2. Press and hold the reset button for at least five seconds until the light changes
  3. Ensure the condensate pipe (the plastic pipe leading outside) has not frozen during cold weather

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • PCB (Printed Circuit Board)

Related codes

Full explanation for 3 red flashes
4 green flashes

Your boiler has experienced a brief communication glitch between its internal components and should fix itself automatically.

Low DIY-safe £0-120

What to check first

  1. Wait for the boiler to automatically reset itself.
  2. If the flashing continues, press the reset button once.
  3. Ensure there are no external power fluctuations affecting the unit.

Parts commonly replaced

  • Printed Circuit Board (PCB)
Full explanation for 4 green flashes
5 green flashes

Your boiler is experiencing a temporary communication glitch with its internal computer, but it should fix itself automatically.

Low DIY-safe £0-80

What to check first

  1. Wait for the boiler to self-reset automatically
  2. Monitor the light panel to see if the flashing stops
  3. If the fault persists, try turning the control knob to 'Reset' and then back to the desired temperature

Parts commonly replaced

  • No parts usually required
  • Printed Circuit Board (PCB) if fault becomes permanent
Full explanation for 5 green flashes
5 red flashes

Your boiler's computer memory has developed a internal communication error, meaning it can no longer remember how to operate safely.

High Engineer only £250-450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Parameter Storage Unit (PSU)

Related codes

Full explanation for 5 red flashes
6 green flashes

Your boiler has experienced a brief internal glitch and is currently attempting to restart itself.

Low DIY-safe £0-120

What to check first

  1. Wait for the boiler to complete its self-reset cycle
  2. Monitor the control panel to see if the flashing stops and the light turns solid green
  3. If the flashing persists for more than 15 minutes, try turning the power off and back on at the fused spur

Parts commonly replaced

  • None (Temporary glitch)
  • PCB (if error becomes permanent)
Full explanation for 6 green flashes
6 red flashes

Your boiler has encountered a general electrical or internal communication error and has shut down as a safety precaution.

High DIY-safe £180-350

What to check first

  1. Press the reset button for at least five seconds.
  2. Ensure the central heating system pressure is at roughly 1.5 bar.
  3. Switch the main electrical power to the boiler off and back on again.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Spark Electrode
  • Wiring Loom

Related codes

Full explanation for 6 red flashes
Digital codes
110

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

High DIY-safe £100-280

What to check first

  1. Wait for the boiler to cool down completely
  2. Check all radiator valves are open and bleed any trapped air from your radiators
  3. Press the reset button on the boiler control panel

Parts commonly replaced

  • Overheat Thermostat
  • Circulating Pump
  • Temperature Sensor (NTC)

Related codes

Full explanation for 110
125

Your boiler has stopped working because the water isn't moving through the system properly, causing it to overheat and shut down for safety.

High DIY-safe £180-350

What to check first

  1. Check if your system pressure is between 1 and 1.5 bar on the pressure gauge
  2. Ensure all radiator valves are open and not stuck
  3. Gently bleed air from your radiators using a radiator key

Parts commonly replaced

  • Circulation pump
  • Overheat thermostat
  • Flow/Return thermistors

Related codes

Full explanation for 125
127

Your boiler has failed to heat your water tank to a high enough temperature to safely kill off any potential bacteria.

Medium DIY-safe £90-220

What to check first

  1. Check that your hot water cylinder thermostat is not turned down too low
  2. Ensure your central heating programmer is set to allow the hot water to run for at least an hour
  3. Press the reset button on the boiler control panel

Parts commonly replaced

  • Cylinder thermostat
  • External wiring center
  • NTC thermistor

Related codes

Full explanation for 127
133

Your boiler has tried to light several times but has been unable to successfully create or detect a flame.

High DIY-safe £100-£250

What to check first

  1. Check if your gas supply is active by testing another gas appliance like a hob
  2. Ensure your gas meter has credit if you are on a prepayment meter
  3. Press the 'Reset' button on the front of the boiler for five seconds

Parts commonly replaced

  • Ignition Electrode
  • Flame Sensing Probe
  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 133
160

Your boiler has detected that the internal fan, which safely exhausts gases, is not spinning at the correct speed or has stopped working entirely.

High Engineer only £220-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Venturi tube

Related codes

Full explanation for 160
E12

Your boiler has stopped working because water is not flowing through the system correctly to prevent overheating.

High Engineer only £120-280

Parts commonly replaced

  • Central heating pump
  • Flow switch
  • Printed Circuit Board (PCB)

Related codes

Full explanation for E12
E78

Your boiler has lost the ability to monitor its own water pressure, meaning it has shut down to prevent potential damage.

High Engineer only £130-220

Parts commonly replaced

  • Water pressure sensor
  • Sensor wiring harness
  • PCB

Related codes

Full explanation for E78
OFF OFF OFF

Your boiler appears to have no electrical power at all, meaning the display is blank and the unit cannot start up.

High DIY-safe £90-350

What to check first

  1. Check if the boiler's power switch is turned on
  2. Check your home's main fuse box (consumer unit) for a tripped circuit breaker
  3. Check the 3-amp fuse in the fused spur switch next to the boiler

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • External Fuse
  • Control Knob/Interface Frame
Full explanation for OFF OFF OFF
ON OFF ON

Your boiler has failed to light the gas flame after several attempts and has shut itself down for safety.

High DIY-safe £120-350

What to check first

  1. Check that your gas prepayment meter has credit (if applicable)
  2. Ensure other gas appliances in the home are working correctly
  3. Press the 'Reset' button on the front of the boiler for five seconds

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Printed Circuit Board (PCB)
Full explanation for ON OFF ON
Status & diagnostic codes

1 operating states & engineer diagnostics

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

1 green flash Status Your boiler is working normally and has simply reached its target temperature, so it is pausing until the heat is needed again.