Why converters matter
A catalytic converter contains small amounts of platinum-group metals that are recovered when it is recycled. That is why converter theft is common, and why the converter is part of how a whole car is valued. How much any given converter is worth varies widely by vehicle and over time, so be skeptical of anyone quoting a converter price sight unseen.
Should I cut it off before I junk the car?
Our advice: leave it on. The car is quoted as a whole vehicle, and the converter is part of it. Cutting it off yourself is dirty, sometimes dangerous work on an exhaust that may be rusted solid, and selling a detached converter on its own brings its own Colorado paperwork (below). A complete car is simpler for everyone.
What if the converter was stolen?
It happens, especially to cars that have been parked a long time. Just say so when you ask for a quote. A missing converter changes the offer, and it is far better to know that before pickup than to have the number change in your driveway. If it was stolen recently, you may also want to file a police report for your records. See how offers are figured.
Colorado's rules for detached converters
Colorado regulates purchases of detached catalytic converters under C.R.S. 18-13-111. Junk shops, salvage yards, and dealers that buy a converter on its own have to record the seller's ID, get a signed affidavit that the seller owns it or is entitled to sell it, note the delivery vehicle's plate, and keep a photo or video record. Cash is limited to transactions of $300 or less unless the payment process photographs the seller. The statute carves out converters that come attached to a whole vehicle bought by an auto parts recycler that reports the vehicle to the federal title system (NMVTIS).
The point for a seller: a converter on its own draws extra scrutiny for good reason. A converter on the car it came from is just part of the car.