Baxi Netaheat Fault codes & diagnostics

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

Regular Natural Gas 9-23 kW 1978-1996 Discontinued

Replaced by: Potterton Profile

No manual available yet We don't hold the official service manual for this model yet. We're sourcing it — check back soon.

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.
6 High 1 Medium 3 Low
Just want the most common Baxi Netaheat faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 10 documented codes

Tap any card for details

1 red flash

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

High DIY-safe £120-280

What to check first

  1. Check that your radiator valves are open
  2. Ensure the system pressure is between 1 and 1.5 bar on the gauge
  3. Try resetting the boiler using the dial or reset button

Parts commonly replaced

  • Temperature Sensor (NTC Thermistor)
  • 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 itself down to prevent damage.

High DIY-safe £120-280

What to check first

  1. Turn off the boiler at the main electrical switch and wait 15 minutes for it to cool down.
  2. Check that your radiator valves are open and that there is enough water pressure in the system.
  3. Press the reset button firmly; if the red light persists or recurs, you must call a professional.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Thermistor

Related codes

Full explanation for 2 red flashes
3 green flashes

Your boiler has lost its flame briefly and will try to restart itself, but it may be struggling to keep the burner lit.

Medium DIY-safe £100-250

What to check first

  1. Check that your gas supply is turned on (check other gas appliances)
  2. Press the reset button once the boiler stops attempting to restart
  3. Monitor the boiler to see if the fault progresses to a solid red light

Parts commonly replaced

  • Flame sense electrode
  • Gas valve
  • PCB

Related codes

Full explanation for 3 green flashes
3 red flashes

Your boiler has tried to light several times but cannot start up, meaning you currently have no heating or hot water.

High DIY-safe £100-280

What to check first

  1. Check that your gas pre-pay meter is in credit
  2. Ensure any gas isolation valves are turned to the 'on' position
  3. Press and hold the reset button for five seconds to restart the ignition sequence

Parts commonly replaced

  • Ignition electrode
  • Flame sensing probe
  • Gas valve

Related codes

Full explanation for 3 red flashes
4 green flashes

Your boiler has experienced a brief communication hiccup between its internal electronic parts and should fix itself automatically.

Low DIY-safe £0-120

What to check first

  1. Wait for the boiler to self-reset automatically
  2. Monitor the display to see if the flashes stop
  3. If the lights persist, turn the power to the boiler off and back on once

Parts commonly replaced

  • None (Software reset)
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 4 green flashes
4 red flashes

Your boiler has detected that the internal fan, which clears waste gases out of the flue, is not spinning correctly or has lost power.

High Engineer only £220-450

Parts commonly replaced

  • Fan assembly
  • Air pressure switch
  • PCB (Control board)

Related codes

Full explanation for 4 red flashes
5 green flashes

Your boiler has experienced a brief electronic 'hiccup' or data error and is trying to correct itself automatically.

Low DIY-safe £0-280

What to check first

  1. Wait up to 10 minutes for the boiler to automatically reset itself.
  2. If the flashing continues, turn the power switch to the boiler off and then back on again.
  3. Ensure there are no external electrical appliances causing interference near the boiler.

Parts commonly replaced

  • Printed Circuit Board (PCB)

Related codes

Full explanation for 5 green flashes
5 red flashes

Your boiler's internal memory unit has developed a communication fault, meaning the control board no longer knows how to operate the system safely.

High Engineer only £180-350

Parts commonly replaced

  • Parameter Storage Unit (PSU)
  • Main Control PCB

Related codes

Full explanation for 5 red flashes
6 green flashes

Your boiler has encountered a minor temporary glitch and is currently pausing before trying to restart itself automatically.

Low DIY-safe £0-120

What to check first

  1. Wait for the boiler to complete its automatic self-reset cycle
  2. If the error persists, turn the boiler power switch off and back on again
  3. Monitor the display to see if the flashing returns

Parts commonly replaced

  • Control Board (PCB)
  • External Wiring

Related codes

Full explanation for 6 green flashes
6 red flashes

Your boiler has encountered a general electronic fault and needs to be reset to try and clear the error.

High DIY-safe £100-350

What to check first

  1. Locate the reset button or selector switch on the front control panel
  2. Turn the selector to the reset position and hold for 5 seconds
  3. Release the switch and wait for the boiler to attempt a restart

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

Full explanation for 6 red flashes
Status & diagnostic codes

1 operating states & engineer diagnostics

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

1 green flash Status Your boiler has reached its set temperature and is temporarily pausing its burner; this is a completely normal part of its operation.