Symptoms
- Rattling or buzzing noise that changes with engine RPM
- Noise worse on cold starts or over bumps
- Sound seems to come from underneath, not the engine bay
- Rattle stops or changes when you tap the underside
Likely causes
- CommonLoose exhaust heat shieldThin metal shields rust and their clips break, letting them vibrate against the pipe.
- CommonLoose heat shield on catalytic converterThe shield around the catalytic converter is a very common rattle source.
- PossibleDebris caught in the underbodyA stick, rock, or piece of road debris can get lodged and rattle.
- PossibleLoose exhaust hanger or bracketA broken rubber hanger lets the exhaust pipe swing and hit nearby metal.
- Less commonLoose splash shield or underbody panelPlastic underbody panels can crack or lose clips and flap or rattle.
What to do
- Park over a flat area and, with the engine off and cool, look underneath for a shield you can wiggle by hand.
- Check the area around the catalytic converter and muffler first, since shields there rattle most often.
- Look for any obviously loose or dragging metal pieces along the exhaust.
- If you find a loose shield, you can often silence it temporarily with high-temperature clamps, wire, or by bending it away from the pipe.
- Check exhaust hangers (rubber mounts) for cracks or tears that let the pipe move too much.
- If the rattle continues or you can't reach the source safely, have a shop secure or remove the offending shield.
Tools and parts
- Flashlight
- Pliers
- Gloves
Heat shield clamp or repair kitSearch: “exhaust heat shield clamp”
Exhaust hangerSearch: “exhaust rubber hanger for [your car]”
When to call a pro
A muffler shop can quickly secure or trim a rattling shield; get it looked at if the rattle is constant, since a shield can eventually fall off and drag.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.