Viessmann Boiler Error Code F4: Burner Lockout (No Flame Signal)
Burner control unit detected no ionization flame signal after ignition sequence.
Equipment TypeVitodens 100-W / 200-W Gas BoilerBrand: Viessmann
Fault SeverityCriticalSystem Lockout Active
Estimated Repair Cost€110 – €340Parts & Certified Labor
🚨 Symptoms of Viessmann Error F4
- Red fault indicator illuminated and F4 displayed
- Heating and domestic hot water shut off
- Lockout persists after resetting
🔍 Root Causes for Viessmann Code F4
- Defective or carbon-fouled ionization electrode
- Ignition cable damaged or disconnected
- Gas valve closed or insufficient gas flow
- Condensate drain line blocked
🛠️ How to Reset & Troubleshoot Viessmann Error F4
- Verify gas shutoff valve is open
- Check condensate trap for water backup and clean if necessary
- Press reset button on Vitodens controller
- Replace ionization electrode and ignition harness
Frequently Asked Questions — Viessmann Code F4
What does Viessmann error code F4 mean?
Viessmann code F4 indicates: Burner control unit detected no ionization flame signal after ignition sequence.
How do I reset error code F4 on Viessmann?
Turn off the electrical circuit breaker or isolator to the unit for at least 5 minutes to discharge the capacitors and reset the microprocessor. If the code reappears immediately upon restarting, professional inspection is required.
What causes error code F4 on Viessmann systems?
Common triggers include: Defective or carbon-fouled ionization electrode, Ignition cable damaged or disconnected, Gas valve closed or insufficient gas flow.