An airfryer or pressure cooker is faulty when its performance drifts noticeably from what it used to do: the airfryer stops heating as well, or the pressure cooker stops building pressure as fast, and the problem repeats across several uses rather than happening once.
What signals a fault in an airfryer?
The most common sign is a recipe that used to take 18-20 minutes now staying undercooked after 25-30, which usually means the heating element has lost power. A burning-plastic or electrical smell from the basket, a repeating error code on the display, or a fan noise that turns into an odd squeal all point the same way.
A non-stick coating that has scratched through to bare metal, or that is bubbling and flaking, is also part of the fault picture; food can pick up loose particles from the coating, so the basket should be replaced. A lid or drawer that no longer closes fully, or a unit that vibrates while running, should not be ignored either.
What signals a fault in a pressure cooker?
A steady trickle of steam from the valve even with the lid fully locked is the clearest sign the pot can no longer hold pressure, and meals take far longer to cook as a result. A safety valve that never engages, or one that reacts with excessive pressure during normal cooking, is a serious fault and the pot should not be used in that state.
A locking mechanism that stays loose and no longer gives the usual firm click when closed is also a fault sign. A slight warp or bulge in the base means it no longer sits flush on the hob, which slows heating and throws off the pressure balance.
On either appliance, any warming, sparking or melting around the cord or plug means it should be unplugged and stopped immediately; that alone is enough of a fault to take it to a repair technician or, under warranty, back to the manufacturer. A small delay or slightly different sound is usually fixed with maintenance, but pressure loss and electrical signs should be dealt with without delay.
It is also worth telling a genuine fault apart from misuse. Overfilling an airfryer basket, using far less oil than a recipe calls for, or skipping preheating can spoil results even in a perfectly working unit. In a pressure cooker, running the lid for a long time without oiling the gasket, or operating the valve without cleaning it, can mimic a pressure fault without one actually being present, which is why the first step is always checking the gasket and valve for grease or debris.
Skipping the periodic maintenance listed in the manual, such as removing and washing the basket and valve or checking the gasket, is behind most cases that look like a fault but are really built-up grease or residue. If the same symptoms persist after a proper clean, the appliance can be treated as genuinely faulty and taken to an authorised service centre or a qualified repair technician; opening up the electrical parts yourself both voids the warranty and carries real risk.