Ideal Boiler Fault Codes: Quick Guide (Logic, Logic+, Logic Max, Vogue & others), Boiler Repair, Plumbing & Heating Services
Safety first: if you smell gas, hear arcing, or the boiler keeps locking out, switch off and call a Gas Safe engineer.
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Common Ideal codes (what they mean & what to do)
| Code | Plain-English meaning | Quick next step |
|---|---|---|
| F1 | Low system water pressure | Check pressure ~1.0–1.5 bar; top up if you know how. If it keeps dropping, there may be a leak or sensor issue. |
| F2 | Flame loss during operation | Try one reset; check gas supply/credit; if it returns, call an engineer (ignition, gas, or condensate/flue issue). |
| F3 | Fan fault | Engineer to test/replace fan and wiring. |
| F4 / L4 | Flow thermistor fault (sensor) | Power-cycle once; engineer to test/replace NTC/wiring. |
| F5 / L5 | Return thermistor fault (or “too many resets” on some models) | If L5 appears after repeated resets, leave boiler off ~15 min; engineer to inspect sensors/PCB. |
| F6 | Outside sensor fault | Check if external sensor is fitted; engineer to test/replace. |
| F7 | Low mains voltage | Do not keep resetting; resolve supply issue / call electrician if persistent. |
| F8 / F9 / L8 / L9 | PCB/configuration fault | Engineer diagnostics; may require board configuration or replacement. |
| FD | No water flow | Check all radiator valves open; top up system if low; persistent = engineer. |
| LF | Ignition fault / lockout | One reset only; if it returns, engineer to check ignition, gas rate, condensate. |
| L1 | Flow temperature overheat / no water flow | Let it cool; ensure pressure is ~1–1.5 bar, rads open; if recurring, engineer. |
| L2 | Ignition lockout / flame loss | Try a single reset; check gas/credit; call engineer if it returns. |
| L6 | False flame lockout (flame detected when there shouldn’t be) | Engineer to check electrodes/PCB/gas valve safety. |
| LC | Multiple resets within 15 minutes | Power off, wait, then one restart; if LC repeats, engineer visit. |
| H9 / HA / LA | Overheat | Switch off and book an engineer; likely circulation/thermostat issue. |
Names/behaviour vary slightly by model (e.g., Logic vs Vogue). For exact wording, check Ideal’s official fault-code help and your model manual.
What you can try (safe checks)
- Repressurise to ~1.0–1.5 bar (F1/L1/FD related).
- One reset only to clear a transient lockout (L1/L2/LF).
- Check pay-as-you-go gas credit (L2/LF).
- Bleed radiators if many are cold at the top (then re-pressurise).
If a fault returns or involves gas, ignition, electronics, or sealed components, book a Gas Safe engineer.
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Need help fast?
24/7 emergencies, ~1-hour ETA. Certified plumbing, heating/boiler, drainage, gas and electrical engineers—transparent pricing, fully insured, UK-wide. Call or book online.