Intergas Boiler Error Code 5
With code 5 the boiler does see a flame, but the signal is too weak or unstable. Causes include a blocked condensate drain, an incorrect gas adjustment or poor earthing. Check the gas supply and the flue outlet outside and reset once; after that it is a job for an installer.
Also shown as: 05
Applies to: Intergas HRE and Kombi Kompakt
Common causes
- Blocked or frozen condensate drain
- Incorrect CO2 adjustment of the gas valve
- Poor earthing of the ionisation electrode or the boiler
- Flue gas being drawn back into the flue (back draught or recirculation)
What to check, in order
- Check that the gas tap is fully open and that other gas appliances work normally.
- Check outside whether the flue outlet is clear of leaves, nests or ice, and clear the outlet if needed.
- Check that the boiler is plugged into an earthed socket and reset the boiler once.
- If the code returns, have an installer check the ionisation electrode, the condensate drain and the adjustment.
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
Most cases are solved by the checks above. Book a technician 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 5, 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.
Parts that may be involved
Ignition/ionisation electrodeGas valveCondensate drain
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 5
What does 5 mean on a Intergas boiler?
5 means: Poor flame signal: the flame is not detected properly while burning. With code 5 the boiler does see a flame, but the signal is too weak or unstable. Causes include a blocked condensate drain, an incorrect gas adjustment or poor earthing. Check the gas supply and the flue outlet outside and reset once; after that it is a job for an installer.
Can I fix Intergas 5 myself?
Start yourself: the checks on this page cover the causes you can reach without opening the machine up. If they point to a faulty part, testing or replacing it is usually a technician job.
How do I clear Intergas 5?
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.