Common problems guide

The most common Ideal Atlantic Combi problems

The faults most likely to send a Ideal Atlantic Combi into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

59 documented codes
6 most common
5 DIY-safe checks
1 engineer needed

The 6 most common faults

01
F1 High DIY-safe

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

What to try first

Locate the filling loop, which is usually a small silver braided hose or a built-in lever underneath your boiler.Open the valves on the filling loop slowly to allow water into the system while watching the pressure gauge on the front panel.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then ensure the valves are fully closed.

Est. cost
£0-£100
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for F1
02
Low water pressure High DIY-safe

Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.

What to try first

Locate the filling loop, which is usually a silver flexible hose connected to two valves underneath the boiler.Open the valves slowly to allow water into the system until the pressure gauge on the front of the boiler reaches the green zone (typically 1.0 to 1.5 bar).Close both valves tightly to prevent over-pressurisation and check for any visible leaks.

Est. cost
£80-120
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for Low water pressure
03
82 High DIY-safe

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

What to try first

Locate the filling loop, which is usually a flexible silver hose connected to two valves under your boiler.Gradually open the valves to let water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close both valves tightly and ensure the pressure remains steady.

Est. cost
£80-120
Parts
Pressure relief valve, Expansion vessel, Pressure sensor
Full guide for 82
04
Water Pressure High DIY-safe

Your boiler has stopped heating your home or water because the amount of water inside the system has dropped below the required level.

What to try first

Locate the external filling loop, which is a flexible braided hose underneath the boiler.Open the two valves on either end of the hose one by one to let water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (typically 1.0 to 1.5 bar).Close both valves tightly and remove the filling loop if required by your specific model.

Est. cost
£80-150
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for Water Pressure
05
4.5 High DIY-safe

Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.

What to try first

Locate the external filling loop, which is a silver braided hose under your boiler.Open the small valve or tap attached to the hose until you hear water flowing.Watch the pressure gauge on the front of the boiler until it reaches exactly 1.5 bar.Close the valve tightly to stop the water flow.

Est. cost
£80-120
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for 4.5
06
L1 High Engineer

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

Est. cost
£150-300
Parts
NTC Thermistor, Primary Heat Exchanger, Pump
Full guide for L1

on the Ideal Atlantic Combi

Filling loopPressure relief valvePressure sensorExpansion vesselNTC ThermistorPrimary Heat Exchanger

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Ideal shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue

Avoid the next call-out bill

Monthly cover means no unexpected bills when your boiler breaks down.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

See the full 59-code list for the Ideal Atlantic Combi