Fridge
F6
The F6 error code on a Siemens fridge indicates a fault with the internal temperature sensor (NTC sensor), meaning the fridge cannot accurately monitor or regulate its temperature. It’s a moderately serious fault — your food may not be kept at a safe temperature, so act promptly.
What does this error mean?
The F6 code tells you the fridge’s NTC (Negative Temperature Coefficient) thermistor — the sensor responsible for reading the internal cabinet temperature — is either giving a reading outside the expected range or has failed entirely. Without an accurate temperature reading, the fridge’s control board cannot properly manage the compressor and cooling cycle. This can result in the fridge running continuously, not cooling enough, or freezing food unexpectedly.
Est. repair cost
£10–£25 DIY sensor replacement; £80–£180 for a professional repair (sensor or PCB)
🔍 Likely causes
🛠️ Step-by-step fix
Power reset: Unplug the fridge from the wall socket, wait 5 minutes, then plug it back in. If F6 clears and doesn’t return within a few hours, a temporary glitch was the cause — monitor it closely.
Check for ice build-up: Open the fridge and inspect the back wall and any visible sensor probe for frost or ice. If iced over, switch the fridge off and allow it to defrost fully (place towels down), then restart.
Inspect the sensor wiring: With the fridge unplugged, locate the NTC sensor — usually a small probe clipped to the inside rear wall or evaporator cover. Check that its wiring connector is firmly seated and that there are no visible cuts or burnt marks on the cable.
Test or replace the NTC sensor: NTC sensors for Siemens fridges are available from UK appliance parts suppliers (e.g. eSpares, 4ourhouse) for £10–£25. With the fridge unplugged, unclip the old sensor, plug in the new one, and restore power. This is a safe, tool-free job on most models.
Check your model’s specific sensor location: Refer to your fridge’s user manual or search your model number on Siemens UK’s support pages — sensor placement varies between iQ300, iQ500, and iQ700 series models.
If the error persists after sensor replacement, stop DIY work — the main PCB may be at fault, which requires a qualified engineer.
📞 When to call a professional
If replacing the NTC sensor doesn’t clear the F6 code, call an appliance engineer — the main control board (PCB) is likely faulty, and replacing it involves working with the fridge’s electrical components and requires diagnostic tools. When you call, tell the engineer: ‘My Siemens fridge is displaying error code F6 — I’ve already replaced the NTC temperature sensor and the fault persists, so I suspect a PCB fault.’ This will save time and may reduce the call-out charge.
⚖️ Repair or replace?
A professional repair for an F6 fault — whether sensor or PCB — typically costs £80–£180 in the UK, including parts and labour. If your fridge is under 8 years old, repair is almost always the better financial decision; Siemens fridges are built to last 15+ years. If it’s over 10 years old and the PCB needs replacing (parts alone can be £60–£120), weigh the repair cost against a new mid-range fridge (£400–£700) and consider replacing.