Why Does the Car Key Get Hot After Being Pulled Out?
3 Answers
Normal phenomenon. The heating of the car key is directly proportional to exposure to sunlight. The car ignition lock is made of metal, and the hotter the sun, the more heat it absorbs. The temperature inside a closed car under direct sunlight can reach over 80 degrees Celsius. The thin car key inserted into the ignition lock will quickly heat up, causing the car key to become hot. Light above the car key slot: There is a light above the car key slot, which is not an LED and has a lower color temperature, emitting a warmer glow. After prolonged exposure, the car key heats up. Magnetic field changes: For car keys with anti-theft chips, after the key turns on the ignition switch, the factory-installed electronic anti-theft system automatically detects it. The magnetic coil inside the ignition switch generates heat due to changes in the magnetic field, causing the car key to heat up. This is a normal phenomenon. The excessive current passing through the ignition switch (large currents other than the starter motor that are not safely converted through an intermediate relay) can also contribute to the heating.
I've been driving for over a decade and often encounter situations where the car key feels warm after being pulled out. Generally speaking, this is caused by issues with the internal battery or circuitry of the car key. Remote keys contain a small lithium battery and electronic components; if the battery is aging, short-circuited, or has poor contact, it tends to generate heat during use, and the residual heat hasn't dissipated completely when pulled out, hence the warm sensation. My previous car key had severe heating issues due to loose battery contacts, which was resolved after replacing the battery. I recommend avoiding placing the key in high-temperature environments, such as direct sunlight inside the car, and replacing the battery every 1 to 2 years. During maintenance, check for any corrosion on the contacts—safety first. If the key continues to heat up, visit a professional shop promptly to avoid risks.
As a car enthusiast, I often study the principles of key heating. The main reason a car key feels warm after removal is due to heat generated by internal electronic components during operation, such as the microprocessor and battery in remote keys; excessive current or short circuits can also produce heat, and the slow dissipation after removal makes it feel warm. Common causes include expired battery life, physical impacts causing loose wiring, or high-temperature environments exacerbating the issue. I recommend using original batteries, avoiding frequent button presses to reduce load, and preventing drops to avoid internal damage. If the heating persists, have it checked early to prevent battery leakage and potential safety hazards.
