Your car should hum along rather quietly whether you're on the highway or idling at a spotlight, which is why it's a concern when you can clearly hear a rattle coming from somewhere on your vehicle. It's a good idea to schedule an appointment at your local automotive repair garage as soon as possible — and minimize the amount of driving that you have to do in the meantime. Your mechanic will be able to diagnose and fix the issue, and it could simply be something minor. Here are some automotive issues for which a rattling sound is a common symptom.
Broken Heat Shield
A common reason that you might hear a rattling sound coming from your vehicle is that one part of the heat shield has become detached. This thin metal panel is affixed to the underside of your vehicle and due to issues such as corrosion from road salt, can wear out over time — especially in older vehicles. In this case, you'll mostly hear the sound when you're idling; when you're at highway speed, it's uncommon to hear a rattling heat shield unless it's in extremely rough shape. Either way, this repair is fairly minimal, but it's good to get done so that your vehicle runs more quietly.
Failing Exhaust System
It's also common to hear a rattle when your vehicle's exhaust system is failing. In this case, one or more of the brackets that hold the system in place may have broken due to corrosion, resulting in the exhaust system vibrating enough that it's clearly audible from the driver's seat. The repair job for addressing this issue is typically minor, but it could also indicate problems with the exhaust, especially in the case of older vehicles. Failing to address this rattle in a timely manner can leave you with a bigger repair bill down the road, so it's a good idea to schedule an appointment promptly.
Worn-Out Ball Joints
Worn-out ball joints on a vehicle can provide a wide range of symptoms, including a rattling noise. Depending on the degree of wear, this rattling sound might be more apparent when you're turning — and possibly only when you're turning in one direction. The work required to replace a ball joint isn't overly extensive, but it's a good idea to have a mechanic look at the issue right away. When a ball joint wears out, other parts in the vehicle's front end can also begin to fail, leaving you with more week needing to be done.