What Does This Error Mean?

Cosori air fryer preheat not working is usually because the preheat icon was not toggled on before pressing Start, or the unit is already at the target temperature. Tap the preheat icon to activate it, set temperature and time, then press Start.

Affected Models

Cosori Pro II 5.8 Qt
Cosori Pro Gen 2 5 Qt
Cosori Dual Blaze 6.8 Qt
Cosori Lite 4 Qt

Common Causes

Preheat icon not enabled before pressing Start — cooking begins immediately without preheat
Unit already at or above the target temperature — preheat completes instantly
Target temperature set below 200°F (93°C) — preheat may not activate at very low temps
VeSync app recipe not configured to include a preheat step
Control software glitch requiring a reset

How to Fix It

Enable the preheat icon before pressing Start.

On Cosori models with a preheat button or icon, tap it until it is highlighted or lit. Then set the temperature and time, and press Start. If preheat is not toggled on, the unit skips the preheat phase and begins cooking immediately.
Set a cooking temperature above 300°F (150°C).

The preheat function activates when the target temperature is high enough to benefit from preheating. At very low temperatures, the fryer may reach the set temp so quickly that the preheat appears to be skipped. For standard cooking results, set at least 350°F (175°C) and the preheat phase will be clearly visible.
Wait for the preheat phase to complete.

When preheat is active, the display shows a countdown or a preheat status indicator. The unit beeps and prompts you to add food when the target temperature is reached. Do not press any buttons or open the basket during the preheat phase.
Power cycle the unit.

Unplug the Cosori from the wall for 30 seconds and plug it back in. A power cycle clears software states that can prevent the preheat routine from initializing correctly. Try the preheat sequence again after the reset.
Update firmware via the VeSync app.

Open the VeSync app, go to Device Settings for your fryer, and check for a firmware update. Firmware updates sometimes fix preheat-related bugs introduced in earlier versions. Install any available update and test the preheat function again.

When to Call a Professional

Preheat is a software and settings function — no hardware repair is needed. Contact Cosori support if the heating element does not warm up at all.