Car trouble · Exhaust & noise

Something rattles under my car

A tinny rattle or buzz from underneath, often at idle or at certain engine speeds.

Not urgent

A starting point, not a diagnosis. Most parts stores read check-engine codes and test batteries for free.

Likely causes — tick the parts you want

  1. A loose exhaust heat shield

    most likely · Doable with tools and a free afternoon

    How to check: With the engine off and fully cool, tap the thin metal shields above the exhaust pipe with a rubber mallet. A shield that buzzes or moves is the rattle.

  2. A broken exhaust hanger

    possible · Doable with tools and a free afternoon

    How to check: Look under the car for a torn rubber hanger or a pipe that swings freely when you push it gently with a gloved hand while it is cold.

  3. Broken pieces inside the catalytic converter

    less likely · A mechanic’s job

    How to check: When cold, tap the catalytic converter with a rubber mallet. A rattle like loose gravel inside, often with a rotten-egg smell, means it has broken up.

Be careful

The exhaust gets very hot — only touch it after the car has sat for a few hours. Never get under a car held up only by a jack — set it on jack stands on flat, solid ground and chock the wheels that stay down.

Your car — the counter needs this

If the counter doesn’t have a part, your shopper asks them to order it under your name and messages you the order number. When it comes in, send someone to collect it.

Not quite it?

My car squeals when I start itMy exhaust is suddenly loud
Something rattles under my car — likely causes and the parts · DriverRuns