Bad catalytic converter: is it covered, and is the car worth fixing?

If the car is past that point, the converter is your bill, and the question becomes whether the car is worth the repair or worth more sold as it sits.

Start with the warranty

The rule is in 40 CFR 85.2103. For light-duty vehicles, most emission parts carry a general defect warranty of 2 years or 24,000 miles. A short list of major emission control components gets the longer 8 years or 80,000 miles instead, and that list is how converters are covered.

Before you approve a repair:

1. Check the in-service date and mileage. If the car is under 8 years and 80,000 miles, ask a dealer for that make whether the converter falls under the emissions warranty.
2. Ask about an extension. Makers sometimes stretch coverage on known problems. Our maker warranty extensions guide shows how to look one up.
3. Get the diagnosis in writing. You'll need it whether the repair is covered, paid out of pocket, or skipped.

A failed test isn't the whole diagnosis

A converter flagged at an inspection isn't proof it's finished. California's Air Resources Board is blunt about this in its installer guidance: a smog check result alone isn't sufficient evidence that a catalyst needs replacing.

CARB wants a legitimate, documented reason for a new converter. Its examples are a converter that is malfunctioning, damaged in an accident, leaking exhaust, melted, or has a cracked substrate. When the replacement ties into the Smog Check program, a licensed emission repair technician's diagnosis can establish that need. The installer then has to write the reason on the warranty card.

That's a useful standard anywhere, not just in California. Pay for a real diagnosis before you pay for a part.

Why a dead converter can be a bigger problem

Sometimes the converter is the symptom people see and the engine is the casualty. A 2017 manufacturer service bulletin posted by NHTSA describes what happens when a converter's inner brick becomes plugged and breaks apart: converter material can be pulled back into the engine and wear the piston rings and cylinder walls. The bulletin says misfires and oil consumption are by-products of that material getting into the combustion chamber and cylinder bores.

So if the car is also misfiring or burning oil, ask the shop to check the engine before quoting only a converter. A new converter bolted onto a worn engine may not fix anything. If the engine damage is serious, read selling a car with a blown engine.

Replacement choices and their rules

Not every replacement part is legal on every car. Here is what the official sources say.

The EPA fact sheet also describes when an older car has a legitimate case for replacement: when it's more than 5 years old or past 50,000 miles, or 8 years and 80,000 miles for 1995 and newer vehicles. In other words, once the warranty window has closed.

Don't treat the old $300 to $1,000 figure as a quote. Get a current written estimate for the part your car actually needs.

Will your state's test catch it?

A bad converter matters most where the state tests emissions. Where there is no program, the car may still register, though it won't run as cleanly as it should. This table shows each state's emissions program from its official pages.

Repair or sell: how to decide

Lay out the numbers side by side:

• Covered by warranty? Then the decision is easy: get it repaired under coverage and keep or sell a working car.
• Out of warranty, engine healthy? Compare a current written quote for a legal replacement with what the car is worth once fixed. If the repair is a small share of that value, fixing often pays.
• Out of warranty, misfiring or burning oil? The bulletin above suggests the engine may already be worn. Swapping just the converter won't fix it, and all the repairs together can top the car's value.
• In a state with no emissions program? The converter won't block registration, but a buyer who drives the car will still want to know.

If the converter bill tops the car's value, our repair costs more than value guide helps you set the numbers against each other, and what a junk car is worth covers pricing it as it sits.

Selling it to us

We buy whole non-running and junk cars, including ones with a failed converter. You can sell the whole car as it sits, without replacing the converter first, and pickup is free anywhere in the US.

In your offer request, describe what the shop found: the converter diagnosis, and whether there's any misfire or oil burning. That keeps the offer tied to the car you actually have.

Want to talk it over? Call (877) 421-6008.

After the car is picked up, deal with the plates and your state's sale notice; after you sell has each state's steps.