Catalytic Converter
What it does
Converts harmful exhaust gases into less harmful emissions before they leave the tailpipe.
Possible failure symptoms
A check-engine light, reduced engine performance, a rattling noise from underneath the vehicle, or a sulfur or rotten-egg smell from the exhaust.
Potential consequences
A failing converter can trigger emissions test failures and, if clogged, can restrict exhaust flow enough to reduce engine performance.
Typical repair process
A technician retrieves diagnostic codes to confirm the converter is the cause, rather than an upstream sensor or engine issue, then replaces it.
Parts involved
The catalytic converter itself, and sometimes related oxygen sensors.
Questions to ask a mechanic
Ask what diagnostic codes led to the diagnosis, since a failing oxygen sensor or engine misfire can damage a converter that was otherwise fine — fixing the root cause matters.
How coverage generally treats this
General guidance about how these categories typically work — not a claim about your own coverage.
Manufacturer warranty
Often covered by a separate, longer emissions-related warranty that many manufacturers provide in addition to the standard bumper-to-bumper term — federal emissions warranty minimums exist in the US, so check the vehicle's specific emissions warranty terms rather than assuming the general bumper-to-bumper period applies.
Powertrain coverage
Often not included in a typical powertrain definition, which usually centers on the engine, transmission and drivetrain rather than the exhaust/emissions system.
Exclusionary service contract
Coverage varies by contract; some exclusionary contracts cover it, others explicitly exclude emissions components.
Auto insurance
Ordinary mechanical failure or wear is normally not covered by standard auto insurance — theft of the catalytic converter itself may be covered under comprehensive coverage, which is a different scenario than a failure.
Manufacturer recall
Only applicable if there's an open recall for a specific catalytic converter or emissions-system defect.
Related warning lights
Noticing a related symptom on your own vehicle? The Symptom Explorer shows what other owners of your specific year, make and model have reported to NHTSA.
This is general guidance, not a diagnosis or a repair-cost estimate — we don't have reliable cost data, so none is shown here. A qualified technician should confirm the actual cause and cost for your vehicle.