Vaillant ecoTEC Plus F.67 Error Code — Ignition Fault Caused by PCB or Flame Detection Error

If your Vaillant ecoTEC Plus boiler is showing the F.67 error code, it means the boiler’s PCB (printed circuit board) has detected an abnormal ignition sequence or the flame signal isn’t being read correctly.
Vaillant’s internal diagnostics register F.67 when:

• The PCB fails to recognise a stable flame after ignition, or
• Electrical interference, poor grounding, or internal PCB damage disrupts the ignition process.

In simple terms: the boiler is trying to light, but the electronics cannot confirm the flame – so it shuts down for safety.

Our Gas Safe engineers diagnose F.67 faults caused by several underlying problems, including:

• A failing PCB unable to process ignition or flame signals
• Damaged or contaminated flame sensor
• Loose or corroded ignition wiring
• Blocked burner or poor gas-to-air mix
• Power surges affecting the ignition circuit
• Moisture or heat damage on the control board
• Incorrect polarity or earthing issues

F.67 can appear on boilers that have recently had electrical work, storms, or power cuts.

• Boiler tries to ignite but cuts out within seconds
• You hear clicking or brief ignition before shutdown
• The display flickers or errors appear intermittently
• No heating or hot water

• • Previous or related codes like F.27, F.28, or F.29 may have appeared

⚠️ Do not open the boiler casing or attempt to clean ignition components.

You can safely:

• Reset the boiler once after waiting a few minutes
• Check your gas supply is on and other gas appliances are working normally
• Ensure the boiler has a stable power supply
• Look for signs of leaks or moisture around the casing

If the boiler continues trying to ignite and fails — stop resetting and call a Gas Safe engineer, as repeated attempts can damage the PCB.

When you call Pleasant Plumbers, our Gas Safe engineers will:

• Check ignition voltage and flame signal strength
• Inspect and clean the flame sensor and burner assembly
• Test PCB components responsible for ignition control
• Verify polarity, earthing and mains voltage stability
• Check for moisture, heat damage or loose connections on the board
• Replace the PCB if it’s failing to read the flame correctly
• Complete full combustion and safety checks after repair

Most F.67 faults are resolved either by correcting ignition wiring, cleaning the flame sensor, or repairing/replacing the PCB.

If F.67 appeared after a power surge, storm, or your lights flickered recently, it may be a temporary ignition glitch.
Call our Free Boiler Repair Hotline and we’ll guide you through a safe reset sequence and basic gas checks — completely free.
If the error remains, we can send a same-day Vaillant specialist anywhere in London.

• Keep your boiler serviced annually to prevent burner contamination
• Fit a surge-protection fused spur to protect the PCB
• Ensure proper polarity and earthing on your electrical supply
• Fix early flame or ignition faults before they escalate

Good electrical protection and clean ignition components keep your boiler lighting reliably year-round.