Exhaust System Leak or Heat Shield Rattle
A continuous unusual noise from under the car on a 2019 Nissan Altima is often caused by an exhaust leak, a loose heat shield, or a damaged exhaust component. The noise may be a rattle, hiss, or metallic sound.
Diagnosis Details
Possible Causes
Loose or corroded exhaust heat shield vibrating against the underbody
Exhaust system leak at a gasket, flange, or cracked pipe
Damaged or failing catalytic converter internal structure
Related OBD-II Codes
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What You Should Do
Inspect the underside of the vehicle for loose heat shields, exhaust hangers, or visible damage.
A professional mechanic can perform a thorough exhaust system check and tighten or replace any loose components.
If a leak is suspected, a smoke test or visual inspection is recommended.
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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.
