Intergas Boiler Error Code F003
With F003 the flue gases get too hot, which usually points to a fouled heat exchanger that cannot pass its heat on properly. The boiler stops for safety; cleaning and checking is a job for an installer.
Applies to: Intergas Xtreme
Common causes
- Fouled heat exchanger, so the heat is transferred poorly
- Scale or deposits in the heat exchanger hindering heat transfer to the heating water
What to check, in order
- Note the code and reset the boiler once.
- Check outside whether the flue outlet is clear and not blocked.
- If the code returns, have an installer clean and check the heat exchanger.
Clear the code and test
- Fix what the checks above found first — pressure topped up, a radiator bled, the thermostat set right. Resetting without fixing the cause only brings the code back.
- Make sure the boiler has power and the gas tap at the boiler is open.
- If the water pressure is below 1.5 bar, top it up to between 1.5 and 2 bar with the filling loop, as your manual shows.
- Press the reset button once and watch a full cycle: the boiler should start, heat the radiators or the tap water, and keep running without the code coming back.
When to call a professional
This code usually points to a faulty part, wiring or the control board on a Intergas boiler. Run the checks above to rule out the simple causes, then book a technician — and book one straight away if any of these apply:
- The code comes back after you have run the checks and a test cycle.
- You smell burning, see sparks or scorch marks, or the breaker trips.
- Water is leaking and you cannot stop it.
- The fix needs panels opened beyond what your manual describes, or a part tested with a meter, and you are not set up for that.
When you call, give the brand, the code F003, your model number (on a label on the type plate, usually at the bottom or on the side of the boiler) and the checks you already ran. It shortens the visit.
Repair or replace?
This fault is in professional territory: the fix usually means a major part or board-level work, and the labour adds up. If your machine is already well into its service life, get the repair quote first, then compare it with the price of a current equivalent model before you decide. Paying a large share of a new machine's price to repair an old one is rarely the better deal; replacing a machine over one cheap fault is wasteful too.
Parts that may be involved
Heat exchangerFlue gas sensor S5
Parts are model-specific. Find your model number first — usually on a label on the type plate, usually at the bottom or on the side of the boiler — and match the part to that number before ordering.
Questions people ask about F003
What does F003 mean on a Intergas boiler?
F003 means: Flue gas temperature too high. With F003 the flue gases get too hot, which usually points to a fouled heat exchanger that cannot pass its heat on properly. The boiler stops for safety; cleaning and checking is a job for an installer.
Can I fix Intergas F003 myself?
Only the preliminary checks. Code F003 usually means a part, wiring or the control board has failed, which is a technician job. Run the checks to rule out simple causes before you book.
How do I clear Intergas F003?
Fix what the checks above found first — pressure topped up, a radiator bled, the thermostat set right. Resetting without fixing the cause only brings the code back. Make sure the boiler has power and the gas tap at the boiler is open. If the water pressure is below 1.5 bar, top it up to between 1.5 and 2 bar with the filling loop, as your manual shows.
Sources checked
- Intergas HRE Parameter List / Fault Finding (manufacturer document)
- Warmgarant: Intergas storingscodes
The meaning and checks for this code were checked against the sources above in November 2026. Codes vary by model and region; if your manual lists a different meaning for your exact model, follow the manual.