Common problems guide

The most common Grant Vortex Combi 70 problems

The faults most likely to send a Grant Vortex Combi 70 into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

9 documented codes
6 most common
4 DIY-safe checks
2 engineer needed

The 6 most common faults

01
Amber neon High DIY-safe

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

What to try first

Locate the external filling loop, which is a flexible silver hose connected to two valves under the boiler.Gradually open both valves to let water into the system while watching the pressure gauge.Stop opening the valves once the needle on the pressure gauge reaches the green zone, typically between 1.0 and 1.5 bar, then tightly close both valves.

Est. cost
£80-150
Parts
Filling loop, Pressure gauge, Pressure relief valve
Full guide for Amber neon
02
Amber neon lit High DIY-safe

Your boiler has stopped working because the water pressure inside the system has dropped below the required level.

What to try first

Locate the external filling loop, usually two silver flexible hoses connected to the pipework under the boiler.Open the valves on the loops slowly until you hear water entering the system.Watch the pressure gauge on the front of the boiler and close the valves once the needle reaches the green zone, typically between 1 and 1.5 bar.

Est. cost
£0-£120
Parts
Pressure relief valve, Pressure gauge, Expansion vessel
Full guide for Amber neon lit
03
Lock-out reset button is lit High DIY-safe

Your boiler has detected a problem with the combustion process and has safely shut itself down to prevent any hazards.

What to try first

Check your external fuel supply level (if oil) to ensure the system is not starved of fuel.Wait five minutes to allow the system to clear, then firmly press the illuminated reset button once.If the boiler fails to restart after one attempt, do not repeatedly press the button as this can cause flooding of the combustion chamber.

Est. cost
£120-250
Parts
Photocell, Ignition electrodes, Oil burner pump
Full guide for Lock-out reset button is lit
04
Burner Lock-out High DIY-safe

Your boiler has stopped working because it failed to light the flame safely, and it now needs a manual reset to try restarting.

What to try first

Check your oil tank is not empty and the fuel supply valve is open.Wait for the red light on the burner to illuminate, then press and hold the reset button for 3 seconds.If the boiler tries to start but stops again, do not force repeated resets.

Est. cost
£120-250
Parts
Photocell, Ignition electrodes, Oil burner nozzle
Full guide for Burner Lock-out
05
Lock-out reset button lit High Engineer

Your boiler has stopped working because it failed to ignite, causing a safety mechanism to shut the burner down.

Est. cost
£120-250
Parts
Photocell, Ignition electrodes, Oil nozzle
Full guide for Lock-out reset button lit
06
Red neon High Engineer

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

Est. cost
£120-250
Parts
Overheat thermostat, Central heating pump, PCB
Full guide for Red neon
Parts most often replaced

on the Grant Vortex Combi 70

Filling loopPressure gaugePressure relief valveExpansion vesselPhotocellIgnition electrodes

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 Grant 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
See the full 9-code list for the Grant Vortex Combi 70

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →