Firebird boiler error codes alert you to specific faults in your oil fired heating system. The most common ones include thermistor faults (E1, E2, E3), burner lockout (E5), and flow issues (E6). These codes help UK homeowners and landlords identify problems quickly.
Firebird Boiler Error Codes: A Quick Overview
Firebird boiler error codes provide clear information about faults in your oil boiler. Here is a comprehensive table with the full list of common error codes and their meanings.
| Error Code | Meaning |
| E1 | Control thermistor fault |
| E2 | Flue thermistor fault |
| E3 | Flue thermistor fault |
| E5 | Burner lockout or fault |
| E6 | Low water pressure or flow issue |
| E7 | Overheat or safety thermostat fault |
| E8 | Low oil level or supply issue |
| E9 | Control board or communication fault |
Firebird Boiler Error Codes: Causes & How to Fix
Firebird boiler error codes cover the main issues that can affect oil heating systems and knowing them helps you respond effectively. We explain each one in detail below.
E1 Control Thermistor Fault
E1 on your Firebird boiler means the main temperature sensor is not working correctly. This sensor tells the boiler how hot the water is so it can control the burner properly.
Causes
The sensor can fail after years of heat cycles, wiring can loosen from boiler vibration, or corrosion in the boiler room can damage connections. Scale buildup in the system can also affect sensor accuracy over time.
How to Fix
- Turn off the boiler at the mains isolator.
- A qualified engineer locates the control thermistor and tests its resistance.
- The faulty sensor is replaced with a genuine Firebird part.
- All wiring is inspected, cleaned, and reconnected securely.
- The boiler is restarted and run through test cycles while temperatures are monitored to confirm accurate readings.
E2 or E3 Flue Thermistor Fault
E2 or E3 indicates a problem with the sensor monitoring flue gas temperatures for safe operation.
Causes
Soot buildup on the sensor from poor combustion, a partially blocked flue restricting flow, or wiring damage from heat or rodents can cause these codes. Lack of regular servicing often leads to excessive soot in oil boilers.
How to Fix
- The boiler is safely isolated.
- An engineer cleans the flue and inspects the thermistor.
- A faulty sensor is replaced.
- The full flue system is checked for blockages and proper venting.
- Combustion analysis is performed and the boiler is tested for stable operation.
If your Firebird shows recurring error codes, it may be worth considering a modern upgrade. At Eazy Heat we help many customers transition to new boilers that offer better efficiency and fewer faults.
E5 Burner Lockout
E5 means the burner has failed to fire or has locked out for safety.
Causes
Blocked oil filter, empty or low oil tank, air in the oil line after a delivery, dirty nozzle, or faulty ignition electrodes are common causes. Problems with the oil pump or control box can also prevent proper burner operation.
How to Fix
- Check the oil tank level and supply valve.
- Press the reset button on the burner control once.
- An engineer cleans or replaces the oil filter and nozzle.
- The oil line is bled to remove air pockets.
- Ignition components are tested and the burner is run through several cycles to ensure reliable firing.
E6 Low Water Pressure or Flow Issue
E6 signals insufficient water pressure or flow in the heating circuit.
Causes
Leaks in pipes or radiators, a failing circulating pump, air locks, or sludge buildup restricting flow are typical reasons. In larger systems with many radiators, restrictions build up if the system is not flushed regularly.
How to Fix
- Check the system pressure gauge and top up if low.
- Bleed all radiators thoroughly.
- An engineer tests the circulating pump and replaces it if necessary.
- The system is power flushed to remove sludge.
- Flow rates are verified and the boiler is reset and tested.
E7 Overheat or Safety Thermostat Fault
E7 means the boiler has detected overheating and the safety thermostat has activated.
Causes
Restricted water flow from closed valves or blockages, a faulty pump, or heavy scale in the heat exchanger can cause this. A malfunctioning thermostat sensor can also give false readings.
How to Fix
- Ensure all valves are open.
- Bleed the system.
- An engineer checks flow and cleans or flushes the heat exchanger.
- The safety thermostat is tested and replaced if faulty.
- The boiler is run and temperatures monitored closely.
E8 Low Oil Level or Supply Issue
E8 indicates a problem with the oil supply reaching the burner.
Causes
Low oil in the tank, blocked fuel line or filter, or a faulty oil pump are the main causes. Air leaks in the oil line or a kinked pipe can also interrupt supply.
How to Fix
- Refill the oil tank if low.
- Check the fuel line for kinks or blockages.
- An engineer cleans the filter and bleeds the line.
- The oil pump is tested and replaced if weak.
- The burner is tested for consistent oil delivery.
E9 Control Board or Communication Fault
E9 points to a problem with the main control board or communication between components.
Causes
Electrical surges, age related failure of the board, or loose connections can cause this. Water ingress or corrosion in the boiler room can damage electronics.
How to Fix
- The boiler is isolated.
- An engineer inspects all connections and the control board.
- Faulty boards are replaced.
- Electrical supply is checked for stability.
- The system is reprogrammed and tested fully.
Looking for a New Boiler Quote?
Frequent firebird boiler error codes can become a financial burden. Many UK property owners choose new boiler installations for long term reliability and efficiency gains.
At Eazy Heat, we provide expert new boiler installations for homeowners and landlords throughout the UK. Get in touch today for a free online boiler quote. Let us help you enjoy reliable heating without the stress of frequent faults. Your comfort is our priority.
FAQs
How often should Firebird oil boilers be serviced?
Annual servicing by a qualified technician is recommended to prevent error codes and maintain safe operation.
Can I use biofuel with my Firebird boiler?
Some models are compatible with certain biofuels, but check with an engineer for your specific unit.
Are Firebird boilers suitable for larger homes?
Yes, properly sized models work well in bigger properties with good oil supply.
What should landlords do when error codes appear in rentals?
Arrange prompt professional repairs to ensure tenant comfort and legal compliance.
Do newer oil boilers have better error code diagnostics?
Modern systems often include improved monitoring and fewer common faults for homeowners and landlords.