Reading a spark plug is a great way to check your engine's health. Mechanics often read spark plugs to diagnose fuel mixture, ignition, and engine condition. Here's a clear guide for 5 Reasons Your Volkswagen Engine Is Shaking When Idle PPTX Signs of Bad and Fouled Spark Plugs Autolite Engine vibrations can be alarming and indicate an underlying problem in your car. Here are the key causes of engine vibration while driving or idling: 1. Spark Plug Damage: Damaged spark plugs Car Shaking at Idle: 8 Causes and When to See a Mechanic (2026 Guide) Common Symptoms of Bad Spark Plugs & Why You Shouldnt Ignore Them! , Bad spark plugs can seriously affect your cars performance and even lead to engine damage. Here are the key warning signs to