Can leaving key in ignition cause a fire?

Yes, leaving a key in the ignition can potentially cause a fire, especially if there are underlying electrical issues or if the ignition system malfunctions. In some cases, a short circuit could occur, leading to overheating and igniting nearby materials. Additionally, if the vehicle is parked in a hot environment, the ignition components might overheat, increasing the risk of a fire. It's always best to remove the key when leaving the vehicle unattended to minimize risks.