The software in John Deere tractors locks farmers and independent technicians out of making many repairs, forcing farmers to turn to dealership technicians -- and the delays and inflated repair bills that come with them.

Not only are Deere's repair restrictions bad for farmers -- they appear to be illegal. The Clean Air Act requires that makers of nonroad engines, including those in tractors and combines, "state clearly in your written maintenance instructions that a repair shop or person of the owner's choosing may maintain, replace, or repair emission-control devices and systems."

John Deere restricts access to the software needed to make many repairs, emissions systems included. When farmers can't repair their emissions systems, they are left with two bad options: risk losing their crop while waiting days to weeks for a dealer fix, or upload illegal software that allows them to bypass emissions controls so that they can get back to work.

I urge you to support farmers and the environment by investigating John Deere's repair restrictions and taking necessary action to bring the company into compliance with emissions law.