Tumble Dryer
F09
The F09 error code on a Siemens tumble dryer indicates a fault with the appliance’s heating system — specifically, a problem the dryer is detecting with its NTC temperature sensor or heating circuit. It’s a moderately serious fault: your dryer may run but produce no heat, or it may stop mid-cycle entirely.
What does this error mean?
F09 signals that the dryer’s control board has detected an abnormal reading from the NTC (negative temperature coefficient) sensor, which monitors the drum’s internal temperature during the drying cycle. When this sensor reads a value outside the expected range — either too high, too low, or no signal at all — the machine throws F09 and cuts the cycle to prevent overheating or damage. In plain terms: the dryer can’t confirm it’s heating safely, so it stops.
Est. repair cost
£80–£150 professional repair; £10–£25 DIY NTC sensor replacement (part only)
🔍 Likely causes
🛠️ Step-by-step fix
Reset the dryer first: unplug it from the mains, wait 10 minutes, then plug back in and run a short cycle. A temporary sensor glitch can clear itself after a full power reset.
Clean the lint filter thoroughly: remove the filter (usually inside the door rim), pull off all lint by hand, then rinse under warm water, and leave to dry completely before reinserting.
Clean the condenser unit: locate the condenser behind the bottom kick plate, release the catches, pull it out, and rinse it under a tap until water runs clear. Refit securely. Do this every 1–2 months as routine maintenance.
Check the condenser housing cavity: once the condenser is out, use a vacuum cleaner with a narrow nozzle to remove any lint buildup from inside the cavity — blockages here are a very common cause of heat faults.
If the error persists after steps 1–4, the NTC sensor or wiring is likely at fault. The NTC sensor is a small, inexpensive part (typically £10–£25), but accessing it requires removing the back or drum panel — if you’re confident with appliance DIY and have unplugged the machine, check the sensor connector for loose or corroded terminals first before replacing the part.
Do not attempt to open the electrical control board housing or test the heating element with a multimeter unless you are a qualified electrician or appliance engineer — stop here and call a professional.
📞 When to call a professional
Call an appliance engineer if the error returns after a full reset and a thorough clean of both the lint filter and condenser. Tell them you’re seeing F09 on a Siemens tumble dryer and that you’ve already ruled out blockages — this helps them arrive with the right parts (NTC sensor, wiring loom, or heating element). Also call immediately if you notice any burning smell, scorch marks, or the drum is getting unusually hot before the error appears.
⚖️ Repair or replace?
A professional repair for an F09 fault typically costs £80–£150 in the UK, covering a call-out, diagnosis, and an NTC sensor or element replacement. If your dryer is under 5 years old, repair is almost always the right call. For machines over 8–10 years old, weigh the repair cost against a new heat-pump condenser dryer (£350–£600) — modern models are significantly more energy-efficient and may save you money long-term on running costs.