Oven
F34
The F34 error code on a Siemens oven indicates a fault with the oven’s temperature sensor (NTC probe) or its circuit — it’s a moderately serious fault that will prevent the oven from heating correctly or at all.
What does this error mean?
F34 means your Siemens oven’s control board has detected an abnormal reading from the temperature sensor, known as an NTC (Negative Temperature Coefficient) probe. This sensor monitors the internal oven temperature in real time and feeds data back to the control board. When the reading falls outside the expected range — either because the sensor has failed, its wiring is damaged, or there’s a control board fault — the oven throws F34 and locks out heating to prevent overheating or unsafe operation.
Est. repair cost
£15–£35 DIY (NTC sensor part only); £80–£160 professional repair (sensor or wiring); £150–£300+ if PCB replacement is needed
🔍 Likely causes
🛠️ Step-by-step fix
Power cycle the oven: switch it off at the wall socket or circuit breaker, wait 5 minutes, then restore power. A transient control board glitch can sometimes trigger F34, and a full reset clears it.
Check the oven’s ventilation: ensure nothing is blocking the vents at the rear or top of the oven. Blocked airflow causes overheating, which can damage the sensor. Clear any obstructions and run the oven again.
Inspect and clean around the NTC sensor probe: the sensor is usually a small metal rod mounted on the interior rear or side wall of the oven cavity. With the oven cold and unplugged, carefully wipe away any built-up grease or carbon from the probe tip using a damp cloth — do not use abrasive cleaners.
Check the sensor connector (if confident): unplug the oven, remove the back panel (consult your model’s service diagram), and visually inspect the NTC sensor’s wiring connector. If it’s visibly loose, reseat it firmly. If the wiring is burnt or frayed, do not attempt a repair — call a professional.
Test or replace the NTC sensor: NTC sensors for Siemens ovens are widely available (search your model number + ‘NTC sensor’). With the oven unplugged, the sensor can be unscrewed from the cavity wall and replaced — it’s a straightforward one-screw fix. Confirm the part matches your exact model number before ordering.
If the error persists after a new sensor: the control board (PCB) is likely at fault. PCB replacement or repair is not a DIY task — call an appliance engineer at this point.
📞 When to call a professional
Call a professional if the error returns after replacing the NTC sensor, if you find burnt or damaged wiring inside the oven, or if you’re not comfortable working inside an electrical appliance. When you call, tell the engineer: ‘My Siemens oven is showing an F34 error — I believe it’s an NTC temperature sensor fault.’ This will help them come prepared with the right parts.
⚖️ Repair or replace?
A professional repair for an F34 fault typically costs £80–£160 depending on whether it’s the sensor alone or the PCB. If your Siemens oven is under 8 years old, repair is almost always the better value — Siemens built-in ovens cost £400–£1,200 new. If it’s over 10 years old and the PCB needs replacing (parts can be £100–£200 on their own), replacement becomes worth serious consideration.