When an Ideal boiler finds a problem it stops and shows a code. On most Ideal combi and system boilers (Logic, Logic+, Vogue and similar) it’s a flashing letter and number: F codes are faults and L codes are lockouts. The newest models, such as the Logic Max range, show the same faults in words instead — for example “Ignition Lockout” or “Low Water Pressure”.
📊 Ideal Fault Codes at a Glance
| Code | What it means | Can you check it yourself? |
|---|---|---|
| F1 | Low water pressure | ✅ Yes — top up to 1–1.5 bar |
| F2 | Flame loss / ignition lockout | ✅ Simple checks, then reset once |
| F3 | Fan fault | Reset once — then call an engineer |
| F4 | Flow thermistor (temperature sensor) fault | Reset once — then call an engineer |
| F5 | Return thermistor fault | Reset once — then call an engineer |
| F6 | Outside sensor fault | Reset once — then call an engineer |
| F7 | Low mains voltage | Have an electrician check the supply |
| F0 | Water flow / thermistor fault | Reset once — then call an engineer |
| L1 | Overheating or no water flow | ✅ Check radiator valves and pressure |
| L2 | Flame loss / ignition lockout | ✅ Same checks as F2, then reset once |
| L3 | No water flow | ✅ Check pressure, bleed radiators, reset |
| L5 | Reset limit reached (too many resets in 15 minutes) | ✅ Switch off at the wall for a few seconds |
| L6 | False flame lockout | Reset once — then call an engineer |
| C0 / C2 | Control chip (BCC) fault | Reset once — then call an engineer |
Codes can differ on older or less common models — if your display shows something not listed here, check the user manual that came with the boiler.
💧 F1 — Low Water Pressure
F1 is the most common Ideal code and usually one you can fix yourself. The boiler stops when the pressure falls too low (below about 0.3 bar on Logic Max boilers).
- Turn the boiler off and let the system cool.
- Top up the pressure with the filling loop, following the steps in your boiler’s user manual, until the gauge reads 1–1.5 bar.
- Close both filling loop valves fully, then turn the boiler back on and reset it.
If the pressure keeps dropping, there’s a leak or a faulty part somewhere in the system and it needs an engineer. Step-by-step help: boiler pressure low.
🔥 F2 or L2 — Boiler Won’t Light
The boiler tried to light but couldn’t detect a flame. Ideal’s own checks:
- Do your other gas appliances, such as the hob, work? If none of them do, the problem is the gas supply, not the boiler.
- On a prepayment meter? Check it has credit.
- Is the yellow gas valve under the boiler open? It’s open when the handle points along the pipe.
- Gurgling as it tries to light, especially in cold weather? The condensate pipe may be frozen or blocked — see below.
Then reset the boiler once. If F2 or L2 comes back, stop and call a Gas Safe engineer — the cause is usually a part such as the ignition electrode, flame sensor, gas valve or fan.
🌡️ L1 or L3 — Overheating or No Water Flow
Water isn’t moving round the system properly, so the boiler has shut down to protect itself. Check that the radiator valves and the valves under the boiler are open, check the pressure is 1–1.5 bar, bleed the radiators if they’re cold at the top, then top up the pressure again and reset. If it comes back, the pump, a valve or a blockage in the system needs an engineer.
🔄 How to Reset an Ideal Boiler
- Logic, older Ideal boilers: turn the mode dial to the reset position and hold it there for about 3 seconds.
- Logic+ and Vogue: press the reset button under the display.
- Logic Max and newer: use Restart on the display.
Reset once after doing the checks above. If the boiler is reset too many times within 15 minutes it shows L5 and won’t reset from the button — switch it off at the fused spur on the wall for a few seconds, then back on. If the same code keeps coming back, resetting won’t fix it: call an engineer.
❄️ Frozen Condensate Pipe
In freezing weather the plastic pipe that carries water from the boiler to a drain outside can freeze, and the boiler locks out. Ideal’s advice:
- Warm the frozen part with a hot water bottle, a heat pack or a warm damp cloth, or pour warm water over it from a watering can. Never use boiling water.
- Only thaw pipework you can reach safely at ground level.
- Once the water flows again, reset the boiler. If it still won’t light, call a Gas Safe engineer.
- To help prevent it, keep the heating on low (around 15°C) overnight during a cold snap. More in our frozen condensate pipe guide.
💷 Ideal Boiler Repair Costs in London
| Repair | Rough price |
|---|---|
| Low pressure or condensate fix | £80 – £150 |
| Sensor, thermostat or ignition part | £100 – £250 |
| Diverter valve, fan or pump | £150 – £350 |
| Gas valve or circuit board (PCB) | £200 – £550 |
| Heat exchanger | £300 – £700 |
Rough guide for London, parts and labour. The exact price depends on your boiler and the part. Our engineer gives you a fixed price after seeing the boiler, before any work starts. No VAT added.
Boiler still under its Ideal warranty? Ideal asks you to contact them first, as they deal with warranty repairs; once it’s out of warranty, use any Gas Safe registered engineer. If the boiler is old and keeps breaking down, see repair or replace your boiler.
🏆 Ideal Boiler Repairs with FE Maintenance
- Gas Safe registered, fully insured — every engineer works directly for FE Maintenance, no subcontractors
- Fixed price agreed before any work starts, no VAT added
- Emergency call-outs Monday to Friday, 8am–8pm, from £99 — see emergency gas engineer
- Yearly boiler service from £80 to catch faults early
We cover North, West and Central London, plus Potters Bar and Hatfield. Call 020 8445 1303 or ask for a quote.
General guidance based on Ideal Heating’s published fault code information and user guides, as of October 2026. Codes and reset methods vary between models — your boiler’s user manual is the final word.
Frequently Asked Questions
Ideal Boiler Still Showing a Fault?
A Gas Safe engineer from FE Maintenance can find the cause and fix it, with a fixed price agreed before any work starts.
info@femaintenance.com · 171 Crescent Road, Barnet EN4 9RN