Symptoms
- Rattling or buzzing sound from underneath the car
- Often worse over bumps or at idle
- May come and go depending on speed or engine vibration
- Sound seems to come from the exhaust area rather than the wheels
Likely causes
- CommonLoose exhaust heat shieldThin metal heat shields commonly rust and loosen, rattling against the exhaust pipe or body.
- PossibleLoose exhaust hanger or clampA worn rubber hanger can let the exhaust system shift and rattle against nearby parts.
- PossibleLoose splash shield or underbody panelPlastic underbody covers can crack or lose fasteners and flap or rattle.
- PossibleSomething caught underneath the car (debris)Sticks, plastic bags, or road debris can get lodged and rattle around.
- Less commonLoose suspension component (less common for a simple rattle)Usually causes a clunk rather than a light rattle, but worth ruling out.
What to do
- Have someone gently shake or tap on visible heat shields, panels, and exhaust components (only with the engine off and cool) to see if you can recreate the rattle.
- Look for anything obviously dragging, cracked, or dangling underneath the car, including plastic splash shields.
- Check exhaust hangers (the rubber loops holding the exhaust pipe) for cracking or looseness.
- Drive slowly over a bump if safe to do so and note whether the rattle matches what you hear underneath.
- If you find a loose heat shield, sometimes it can be temporarily secured with high-temperature clamps or wire until properly repaired.
- Check for any debris lodged near the exhaust or underbody that could be causing the noise.
- Have a mechanic put the car on a lift to visually inspect the entire underside if you can't identify the source from the ground.
- Get a loose heat shield or exhaust hanger fixed promptly, since it's usually inexpensive and prevents the rattle from worsening or the part falling off.
Tools and parts
- Flashlight
- Jack and stands (for a closer look, if comfortable)
Exhaust heat shield clamp or hardwareSearch: “exhaust heat shield repair clamp”
Exhaust hangerSearch: “exhaust hanger for [year make model]”
When to call a pro
If you can't locate or reach the loose part yourself, a shop can quickly find and secure it on a lift.
Safety
Use caution
Only inspect underneath a cooled, parked vehicle, and use proper jack stands rather than relying on a jack alone if you need to look underneath.