Error F.67

Safety first:

- Do not attempt internal gas or high-voltage electrical repairs yourself. Working on the gas valve, burner, ignition or PCB carries a risk of fire, explosion, carbon monoxide and electric shock. If in doubt, call a Gas Safe registered engineer (or your country's equivalent).

- If the boiler is running but you suspect combustion issues (smell of gas, yellow flame, soot, or fumes), turn the boiler off, turn off the gas supply at the isolation cock and ventilate the area. Evacuate and call a professional immediately.

- Before touching any electronics, isolate electrical supply at the main fuse and allow the PCB’s large SMPS capacitor(s) to discharge (leave unpowered for at least 10 minutes) and verify voltage with a multimeter if you are trained to do so.

Initial homeowner checks you can safely do:

1. Reset the boiler using the reset button. Note whether the fault returns immediately, intermittently or not at all. Do not repeatedly reset if the fault persists; call an engineer.

2. Confirm gas supply: check other gas appliances (hob, fire) work and that the gas isolation cock is open.

3. Check the boiler’s condensate trap/drain and flue/air inlet for visible blockages or frost that could affect operation.

4. Visually inspect external wiring to the boiler for obvious damage or loose connectors and ensure the boiler has power and the external programmer/room thermostat is calling for heat or hot water when you expect it.

5. Record the exact fault code, when it appears (during ignition, after flame loss, intermittently) and any other codes or symptoms (e.g., fluctuating flow temperature) — this helps the engineer diagnose the root cause.

Safe diagnostic steps for a competent, qualified engineer (do not attempt unless qualified):

1. Recreate fault and observe sequence: determine whether the code appears during ignition, during running, or after a flame loss.

2. Measure flame/ionisation signal at the PCB connector during ignition with a multimeter or oscilloscope to see if a stable expected signal is present. Compare against manufacturer reference values.

3. Check ignition transformer and electrode: verify correct spacing/position and inspect for damage, carbon build-up or misalignment. Replace if faulty.

4. Check wiring harness continuity and insulation to earth for the ionisation lead, gas valve leads and ignition leads. Inspect connectors for corrosion or loose pins.

5. Test gas valve tightness and coil resistances. Carry out a local tightness test to confirm the gas valve is not leaking through.

6. Confirm proper earthing of the boiler and controller; a poor earth can spoil the ionisation signal.

7. Check PCB power rails (e.g., 5 V supply for microprocessor). On ecoTEC Plus boards, degraded electrolytic capacitors (C5, C9 etc.) and failure of the SMPS can cause noisy/unstable measurements and spurious F6x/F7x errors. Inspect the PCB visually for bulged or leaky electrolytic capacitors.

8. If the PCB is suspected, test downstream components and only replace the PCB after excluding wiring, electrode and gas valve faults. If replacing a PCB, ensure any DSN coding/jumper or device-specific settings are transferred and that the coding resistor/jumper from the old board is moved if required.

9. In some cases, repairing the PCB by replacing aged electrolytic capacitors (correct values and polarity — e.g., C5 & C9 commonly 470 µF/35 V or better) has repaired intermittent F6n/F7n faults on older ecoTEC Plus units. Only a competent electronics technician should do this; observe polarity, use suitable replacements and ensure the SMPS is discharged and safe to work on before soldering.

When to call a professional:

- If reset does not clear the fault, if the fault returns repeatedly, or if you are not trained in gas or boiler electronics, stop and arrange a visit from a Gas Safe registered engineer. Any testing or replacement of the gas valve, ignition transformer, electrodes or PCB must be performed by a qualified engineer.

Notes and cautions:

- Do not attempt to bypass flame detection or jury-rig the unit to keep it running. Flame supervision is a mandatory safety feature.

- If a PCB replacement is advised, consider asking the engineer to check and, where safe and economical, replace suspect capacitors or repair the PCB rather than wholesale replacement — some ecoTEC Plus boards suffer capacitor-age faults and repaired boards have restored reliable operation. However, any PCB repair must maintain safety and certification standards.

- Keep a clear log of symptoms, fault occurrences and any actions taken to help the engineer diagnose the problem quickly.