Symptoms
- Extremely loud roar starting the moment the engine turns over
- Noise gets worse when accelerating
- Visible gap or dangling pipe underneath near the middle of the car
- Check engine light comes on shortly after
- Sparks or scraping sounds from underneath while driving
Likely causes
- CommonCatalytic converter cut out and removedThieves target them for the precious metals inside, often cutting both ends in minutes.
- CommonLoose or hanging exhaust after the cutRemaining pipe ends can bang against the underbody or road.
- PossibleDownstream oxygen sensor damaged in the theftWiring for sensors near the converter is sometimes cut or damaged too.
What to do
- Do not drive the car if you can, since the cut pipe can drag, spark, and is very loud; check for a gap or dangling pipe under the middle of the car.
- Take photos of the damage for your insurance claim and the police report.
- File a police report; many departments track these thefts and it's required for insurance.
- Contact your auto insurance company; comprehensive coverage typically covers catalytic converter theft.
- Have the car towed or carefully driven at low speed to a muffler or repair shop for an exact replacement quote.
- Ask about a catalytic converter shield or anti-theft device when it's replaced to reduce the chance of it happening again.
Tools and parts
- Phone camera
- Flashlight
Replacement catalytic converterSearch: “catalytic converter for [year make model]”
Catalytic converter anti-theft shieldSearch: “catalytic converter theft protection shield”
When to call a pro
This is a shop repair; a muffler or general repair shop can weld in a new converter and check nearby wiring and sensors for damage.
Safety
Use caution
Do not drive with a cut, dangling exhaust pipe; it can drag, spark, and create a fire or road hazard, and the fumes can be far louder and more noticeable than normal.