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Technical Diagnostics & Fault Codes • Boilers & Heat Pumps (Vitodens / Vitocal)
Viessmann Fault Codes F2, F4, E4, A9, 06 – Error Code Meaning, Troubleshooting & Repair
Complete diagnostic table of the most common faults for Viessmann (Boilers & Heat Pumps (Vitodens / Vitocal)) with quick troubleshooting steps and links to replacement parts:
Error Code Reference Table for Viessmann and step-by-step repair procedure:
| Error Code | Meaning / Fault Symptom | Most Common Cause & Repair Procedure |
|---|---|---|
| F4 / EE | No flame signal detected during burner start | Worn Viessmann Vitodens ionization electrode, faulty ignition transformer, or low gas supply pressure. |
| F2 | Safety temperature limiter tripped (heat exchanger overheating) | Seized circulation pump, all radiator thermostatic valves closed, or airlocked boiler heat exchanger. |
| 06 / E4 | Low heating water pressure / control board power supply fault | Refill the heating circuit to 1.5 bar and check the expansion vessel pre-charge pressure. |