Common problems guide

The most common Firebird boiler problems

The faults we see most often across the Firebird range — with plain-English causes, what to check first, estimated repair costs, and whether it's a DIY job or needs a Gas Safe engineer. Based on fault-code data across 9 Firebird boiler models.

28 unique codes
9 models covered
8 DIY-safe (top 8)
8 engineer needed

The most common Firebird faults

01
E5 High DIY-safe

Your boiler's burner has stopped working correctly and has entered a safety lockout mode to prevent damage.

What to try first

Check that you have sufficient oil in your storage tank.Ensure the oil supply valve on the tank is fully open.Press the illuminated reset button on the front of the burner once.

Est. cost
£120-350
Parts
Photocell, Oil pump, Control box
Full guide for Enviro 15-20 E5
02
Lockout (Red) High DIY-safe

Your boiler's burner has stopped working and has gone into a safety shutdown mode to prevent further damage.

What to try first

Check that your external oil tank has plenty of fuel.Ensure the oil supply valve is fully open.Press the illuminated red reset button on the burner once to restart it.

Est. cost
£100-£350
Parts
Oil nozzle, Photocell, Fuel pump
Full guide for Enviro Combi 26 Lockout (Red)
03
High Limit Thermostat (Yellow) High DIY-safe

Your boiler has automatically shut down because the water inside has become far too hot, acting as a safety precaution to prevent damage.

What to try first

Check that all your radiator valves are open and not turned to the off position.Inspect the system pressure gauge and top up the water if it is below 1 bar.Wait for the boiler to cool down completely and firmly press the manual reset button located under the control panel cover.

Est. cost
£90-180
Parts
High Limit Thermostat, Circulation Pump, Flow Temperature Sensor
Full guide for Enviro Combi 26 High Limit Thermostat (Yellow)
04
Overheat Condition High DIY-safe

Your boiler has become too hot and has automatically shut itself down as a safety precaution.

What to try first

Allow the boiler to cool down completely for at least 20 minutes.Locate the manual reset button situated at the rear of the electrical control panel.Press the button firmly until you hear a click to reset the safety thermostat.Ensure your radiator valves are open and the system pressure is correct before restarting.

Est. cost
£0-120
Parts
Overheat Limit Thermostat, Circulation Pump, Thermistor
Full guide for Enviro Combi 26 Overheat Condition
05
High limit High DIY-safe

Your boiler has reached an unsafe temperature and has automatically shut down to prevent damage or dangerous overheating.

What to try first

Check that all radiator valves are open and not turned off.Ensure there is enough water pressure in the system by checking the pressure gauge.Press the manual reset button located on the control panel or behind the front cover.

Est. cost
£120-350
Parts
Circulation pump, High limit thermostat, System filter (cleaning/replacement)
Full guide for Enviro System High limit
06
Burner Lockout A High DIY-safe

Your boiler has stopped working because it cannot get enough oil to keep the flame going.

What to try first

Check the oil level in your storage tank to ensure you haven't run out.Inspect the oil supply line valve to make sure it is fully open.Press the illuminated reset button on the burner once; do not press it more than twice.

Est. cost
£90-180
Parts
Oil filter, Photocell, Oil pump
Full guide for Enviro System Burner Lockout A
07
Burner Lockout B High DIY-safe

Your boiler has stopped working because it has detected an issue with its electricity supply or internal wiring.

What to try first

Check if other electrical appliances in your home are working to rule out a power cut.Ensure your boiler's power switch or fused spur is turned on.Press the manual reset button on the burner control box once to see if the system restarts.

Est. cost
£90-250
Parts
Burner Control Box, Internal Wiring Harness, Capacitor
Full guide for Enviro System Burner Lockout B
08
Burner Lockout C High DIY-safe

Your boiler's burner has shut itself down for safety because it failed to light or stay lit properly.

What to try first

Check that you have enough oil in your storage tank.Ensure the oil supply valves are fully open.Press the illuminated manual reset button on the burner once only.

Est. cost
£120-350
Parts
Photocell, Oil nozzle, Ignition transformer
Full guide for Enviro System Burner Lockout C