Firebird Popular 15-20 Fault codes & diagnostics

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

Regular Oil 15-20 kW Discontinued

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Just want the most common Firebird Popular 15-20 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 4 documented codes

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E1

Your boiler's internal temperature sensor has stopped sending the correct information to the control board, preventing the system from heating up.

High Engineer only £120-190

Parts commonly replaced

  • Control thermistor (NTC sensor)
  • Wiring harness

Related codes

Full explanation for E1
E2

Your boiler has detected an issue with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.

High Engineer only £120-190

Parts commonly replaced

  • Flue thermistor (NTC sensor)
  • Connecting wiring harness

Related codes

Full explanation for E2
E3

Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.

High Engineer only £120-£220

Parts commonly replaced

  • Flue thermistor
  • Wiring harness
  • Main control board

Related codes

Full explanation for E3
E5

Your boiler's burner has stopped working and locked itself out, meaning the system has shut down to prevent damage or safety issues.

High DIY-safe £100-250

What to check first

  1. Check that you have enough heating oil in your storage tank.
  2. Ensure the oil supply valve is fully open.
  3. Press the illuminated reset button on the front of the burner once to attempt a restart.

Parts commonly replaced

  • Photocell
  • Oil pump
  • Control box
  • Nozzle

Related codes

Full explanation for E5