Symptom guide
Loud Exhaust Noise
Common causes of sudden or growing exhaust noise under a car.
Quick answer
Loud exhaust noise usually comes from a leak, rusted pipe, loose flange, damaged muffler, or stolen/damaged catalytic converter.
Most likely causes
- Exhaust leak
- Rusted pipe
- Loose flange gasket
- Damaged muffler
- Catalytic converter damage
Basic driver checks
- Notice whether noise is under the hood, middle, or rear.
- Smell for exhaust fumes in cabin.
- Look for hanging exhaust parts.
- Check if noise started after hitting debris.
DIY diagnostic path
- Do not touch hot exhaust.
- Avoid running the engine in enclosed spaces.
- Do not patch near moving or hot parts without proper materials.
- Repair cabin fume leaks promptly.
Common mistakes
- Ignoring exhaust fumes inside the car
- Assuming muffler only
- Driving with dragging exhaust parts
What to tell the mechanic
Describe noise location and whether fumes, rattles, or power loss are present.