Air Fryer
E4
The E4 error code on a Cosori air fryer signals a temperature sensor fault — specifically that the appliance is overheating or cannot read the internal temperature correctly. It’s not a catastrophic failure, but you should stop cooking immediately and not ignore it.
What does this error mean?
E4 indicates that Cosori’s internal thermistor (the temperature sensor) has detected a temperature that’s either dangerously high or is sending a reading outside the normal operating range. The appliance shuts itself down as a safety precaution to prevent a fire or damage to internal components. In most cases, this is a thermal protection response rather than a sign the sensor has physically failed.
Est. repair cost
£60–£110 professional repair; £10–£25 DIY thermistor part (only if you have appliance repair experience)
🔍 Likely causes
🛠️ Step-by-step fix
Turn off and unplug the air fryer immediately — do not attempt to keep cooking through an E4 error. Leave it to cool for at least 30 minutes.
Check the clearance around your air fryer: Cosori recommends a minimum of 5 inches (12cm) of space on all sides and above. Move it away from walls, cabinets, and microwaves.
Once cool, remove the basket and drawer and thoroughly clean them — remove all grease and baked-on food debris. Also wipe out the interior cavity and check for build-up around the heating element (visible at the top interior). Use a damp cloth and mild washing-up liquid; never submerge the main unit.
Reassemble, plug back in, and run a short test cook at a lower temperature (around 160°C) with a lightly filled basket to see if the error returns.
If the error appears again after cleaning and repositioning, perform a factory reset: hold the power button for 5 seconds (consult your specific Cosori model manual, as steps vary slightly by model) to clear any stored fault codes.
If E4 returns after a full reset and you’ve ruled out airflow and debris, the thermistor sensor is likely faulty and will need professional assessment or replacement — do not attempt to open the main unit yourself.
📞 When to call a professional
If the E4 error persists after repositioning the unit, deep cleaning, and performing a reset, the internal thermistor or control board may need replacement — this requires opening the appliance’s main housing, which involves live electrical components and should only be done by a qualified appliance repair technician. When you call, tell them: ‘My Cosori air fryer is showing a persistent E4 error code, which I understand is a temperature sensor fault — it returns even after cleaning and resetting.’ This saves diagnostic time and cost.
⚖️ Repair or replace?
A professional thermistor or control board repair for a Cosori air fryer typically costs £60–£110 in the UK, including call-out — often approaching or exceeding the cost of a new mid-range Cosori model (£70–£130 new). If your air fryer is over 3 years old or out of warranty, replacement is usually the more economical choice. For a newer unit still under Cosori’s 2-year UK warranty, contact Cosori support directly before spending anything.