Exhaust System Leak or Heat Shield Rattle
A continuous unusual noise from under a 2019 Honda Civic is most likely due to a loose heat shield or a small exhaust leak. These components can vibrate or produce a hissing/ticking sound that persists while the engine is running.
Diagnosis Details
Possible Causes
Loose or corroded heat shield rattling against the exhaust or underbody
Small exhaust leak at a gasket, joint, or cracked pipe
Loose or damaged exhaust hanger causing the exhaust system to vibrate
Related OBD-II Codes
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What You Should Do
Inspect the underside of the vehicle for any loose metal shields, especially near the catalytic converter and muffler.
Check for visible exhaust leaks (soot, black residue) and ensure all exhaust hangers are intact.
If the noise is a rattle, tightening or replacing the heat shield often resolves it.
For exhaust leaks, a professional weld or gasket replacement may be needed.
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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.
