Exhaust System or Drivetrain Issue
A continuous noise from under the car on a 2019 BMW 3 Series could be due to an exhaust leak, loose heat shield, or worn drivetrain components.
Diagnosis Details
Possible Causes
Exhaust leak at a joint or gasket, causing a hissing or ticking sound.
Loose or damaged heat shield vibrating against the exhaust or underbody.
Worn center support bearing or universal joint in the driveshaft, producing a clunking or rumbling noise.
Related OBD-II Codes
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What You Should Do
Inspect the underside of the vehicle for visible exhaust leaks, loose heat shields, or drivetrain play.
A professional mechanic should perform a thorough inspection, especially if the noise is metallic or rhythmic.
Related Repairs
Estimated Repair Cost
$100–$500 depending on the cause (exhaust repair or heat shield fix)
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Disclaimer: This AI-generated diagnosis is for informational reference only. Always consult a qualified mechanic for an in-person inspection. AutOwner is not responsible for decisions made based on this information.