Plain-English answers to the most-searched car problems — check engine lights, OBD2 codes, rough idles, and more. Built from real-world data, recalls, and technical service bulletins.
A P0301 code means cylinder 1 is misfiring. Here are the most common causes — from ignition coils to vacuum leaks — and how to diagnose each one.
Read guideA check engine light can mean anything from a loose gas cap to a serious engine problem. Here are the 10 most common reasons it turns on.
Read guideIf your car shakes or vibrates at idle but smooths out at speed, it's usually engine mounts, a misfire, or a vacuum leak. Here are the 7 most common causes.
Read guideA P0171 code means your engine is running lean — too much air, not enough fuel. Here are the most common causes and how to find the leak.
Read guideIf your lights and radio work but the engine won't start, the battery can still be weak. Learn how to narrow down the battery, starter, ignition, fuel and other possible causes.
Read guideAn overheating engine can cause serious damage fast. Here are the 7 most common causes and the steps to take the moment the gauge climbs.
Read guideBrake squeaks can be harmless dust — or a sign your pads are gone. Here's how to tell the difference and what to do.
Read guideThese guides are for informational purposes only. Having a qualified, licensed mechanic inspect your vehicle directly is always the best step. Auto Diagnose AI is not responsible for misdiagnosis or any damage resulting from repairs you perform.