Fridge
F1
The F1 error code on a Bosch fridge indicates a fault with the internal temperature sensor — specifically that the appliance can no longer accurately read the temperature inside the fridge compartment. It’s a moderately serious fault because, without reliable temperature data, your fridge may struggle to keep food safely chilled. In this guide, you’ll learn exactly what’s causing the F1 code, what you can safely check yourself at home, and when it’s time to call in a professional engineer.
What does this error mean?
The F1 error code on a Bosch fridge is a temperature sensor fault. Your fridge relies on a small electronic component called an NTC (Negative Temperature Coefficient) thermistor to constantly monitor the air temperature inside the cabinet. When the control board detects that this sensor is sending a reading that’s out of the expected range — or no reading at all — it throws the F1 error and may trigger an audible alarm. Think of it like a thermometer that’s either broken or has become disconnected: the fridge’s ‘brain’ simply can’t tell what temperature it’s working at, so it raises the alarm. On most Bosch fridge models (including the KGN, KGE, KGS, and Serie 4/6/8 ranges), F1 is specifically tied to the fridge compartment sensor rather than the freezer, which typically has its own separate error code. This fault does not necessarily mean your fridge has stopped cooling — it means it cannot confirm that it’s cooling correctly, which is why it needs to be investigated promptly.
Est. repair cost
DIY sensor replacement: £8–£20 for the part. Professional repair (call-out + labour + sensor): £70–£130. PCB replacement by engineer: £180–£300 including parts and labour.
🔍 Likely causes
🛠️ Step-by-step fix
Step 1 — Perform a hard reset first (no tools needed): Unplug your Bosch fridge from the wall socket completely, or switch it off at the fuse spur. Leave it unpowered for at least 10 minutes — not just 30 seconds — to allow the control board to fully discharge and reset. Plug it back in and check whether the F1 code clears. If the alarm disappears and doesn’t return within a couple of hours, a power surge or glitch was likely the cause. Keep an eye on it for 24 hours.
Step 2 — Check the door seals for damage (no tools needed): Open the fridge door and run your fingers along the entire rubber gasket around the door frame. Feel for cracks, tears, gaps, or sections that have become stiff and no longer press flush against the cabinet. A simple test: close the door on a piece of paper and try to pull it out — it should have clear resistance. If the seal is damaged, warm air ingress can destabilise temperatures and stress the sensor. Replacement door seals for Bosch fridges typically cost £15–£35 and are straightforward to fit yourself.
Step 3 — Defrost the fridge compartment manually (no tools needed): If you can see a build-up of ice inside your fridge or around the back wall, this may be affecting the sensor. Empty the fridge, place towels on the shelves and floor to catch water, and leave the door open with the appliance switched off for 4–6 hours to allow a full manual defrost. Once completely clear of ice, restart the fridge and monitor for the F1 code. This is especially worth trying if the error appeared suddenly after a period of unusually heavy use or if the door was left ajar.
Step 4 — Locate the temperature sensor (basic inspection, no tools needed initially): On most Bosch fridge models, the NTC temperature sensor is a small bullet-shaped or disc-shaped component clipped into the back wall or ceiling of the fridge compartment, or mounted on the evaporator cover behind the back panel. You should be able to see it without removing any panels. Check that the sensor is physically present, not visibly cracked or burnt, and that the wire leading from it is intact and not pinched or chewed.
Step 5 — Check the sensor wiring connector (basic visual check): Follow the wire from the sensor to where it disappears into the back wall of the fridge cavity. If you can see the connector (often a small plastic plug), check it’s firmly seated. Do NOT attempt to access the rear of the appliance, remove panels, or touch any internal electrical components — if you cannot see an obvious loose connection from the inside of the fridge cavity without disassembly, stop here and proceed to Step 6.
Step 6 — Test the sensor with a multimeter (DIY-competent users only, appliance unplugged): If you are comfortable using a multimeter and the sensor is accessible without major disassembly, you can test the NTC sensor’s resistance. Disconnect the sensor’s plug and place the multimeter probes on the two terminals. At room temperature (around 20°C), a healthy Bosch NTC sensor should read approximately 5,000–6,000 ohms (5–6 kΩ). A reading of zero (short circuit) or infinite resistance (open circuit / OL) confirms the sensor has failed and needs replacing. IMPORTANT: The fridge must be unplugged from the mains before you attempt this step.
Step 7 — Replace the NTC temperature sensor (DIY-competent users, appliance unplugged): Replacement NTC sensors for Bosch fridges are widely available from UK appliance parts suppliers such as eSpares, 4ourhouse, and BuySpares, and cost approximately £8–£20. Make sure you have the exact model number of your fridge (printed on the label inside the fridge, usually on the left-hand wall) before ordering, as sensor designs vary. The sensor typically clips or screws into place and uses a simple push-fit connector. Always ensure the fridge is unplugged throughout and that the new sensor is fully clipped in before restarting. If you need to remove any internal back panels to access the sensor, be aware this may void any remaining warranty.
Step 8 — After any repair, monitor the fridge for 24 hours: Once you’ve made a repair or adjustment, restart the fridge and allow it to run for a full 24 hours before considering the issue resolved. Check that the F1 code has not returned, that the fridge is reaching and maintaining its set temperature (use a fridge thermometer — around 3–5°C is ideal), and that no new error codes have appeared.
📞 When to call a professional
You should stop DIY attempts and call a qualified appliance engineer if: the F1 error returns immediately or within a few hours after a hard reset and manual defrost; you’ve replaced the NTC sensor but the fault persists (suggesting a PCB or wiring harness issue); you’re not confident testing with a multimeter or accessing internal components safely; the fridge is no longer cooling at all (food feels warm or is spoiling); or you hear unusual clicking, buzzing, or burning smells alongside the F1 code. When you call, tell the engineer the following: the exact model number of your fridge (e.g. Bosch KGN36VIED), that you are seeing an F1 error code on the display, when it first appeared, and what steps you’ve already tried (reset, defrost, visual inspection). This saves diagnostic time and money. Look for an engineer registered with Which? Trusted Traders or a member of the Domestic Appliance Service Association (DASA). Most independent appliance engineers in the UK charge a call-out fee of £50–£90 which typically includes the first 30–45 minutes of labour.
⚖️ Repair or replace?
For a Bosch fridge displaying an F1 error, the repair-vs-replace decision largely comes down to the age of the appliance and the root cause of the fault. If the fix is simply a new NTC sensor (the most common cause), this is a cost-effective repair at £8–£20 for the part, making DIY repair very worthwhile even on an older machine. If the fault turns out to be a failed main PCB (control board), costs rise significantly — a replacement Bosch PCB can cost £80–£180 for the part alone, plus labour, making professional repair potentially uneconomical on a fridge that is more than 8–10 years old. As a general rule of thumb: if your Bosch fridge is under 7 years old, repair is almost always the right choice — Bosch appliances are well-regarded for build quality and parts are readily available in the UK. If it’s 10 years old or more and the repair quote exceeds £150, it’s worth considering replacement, especially as newer models are significantly more energy-efficient (an A-rated fridge can save £30–£60 per year on electricity bills compared to an older model). New Bosch fridge-freezers in the UK typically start from around £400–£500 for entry-level Serie 2 models, rising to £800–£1,200+ for Serie 6 and 8 models with more features.