Recent guidance documents were issued by EPA related to Diesel Exhaust Fluid (DEF) with the goal of reducing costs for farmers and reducing equipment downtime. Although well-meaning, these announcements have also created some confusion of what they actually state.
We are highlighting two of the most recent announcements in detail below to clarify what was announced.
EPA’s regulatory guidance:
- Seeks to provide real world solutions to ease compliance frustrations,
- Affirms the ability of owners and service providers to TEMPORARILY disable emission systems controls to complete repairs and then REINSTATE those emission systems upon completion of said repair, and
- Authorizes manufacturers to consider NOx sensors to comply with the Clean Air Act.
EPA’s regulatory guidance DOES NOT:
- Amend or change the federal law known as the Clean Air Act to remove or weaken compliance requirements,
- Change or eliminate the requirement for emission systems controls, or
- Change or eliminate the fines or penalties for dealers of $44,549 per violation for failing to return modified equipment to manufacturer specifications as certified by EPA.
INEDA encourages dealers to continue to provide exceptional service to maximize uptime and limit downtime for this and all issues for your customers. We are working with manufacturers and policy makers to provide you with timely and accurate information. EPA also has a webpage devoted to Diesel Exhaust Fluid (DEF), click here.
EPA Guidance on Repairing Emissions Controls
On February 2, 2026, EPA issued guidance in response to John Deere requesting the agency issue guidance confirming that temporary emission control overrides are allowed by EPA.
EPA’s full announcement is available here. It reads in part:
“EPA’s guidance does not change the law, weaken emission standards, or reduce compliance obligations. Rather, it clarifies what the CAA already states, that temporary overrides of emission control systems are allowed when it is for the “purpose of repair” to that equipment to obtain proper functionality. This clarification applies to all nonroad diesel engines equipped with advanced emission control technologies including selective catalytic reduction and inducement systems as well as Diesel Exhaust Fluid (DEF) system repairs.”
Specifically, the guidance states: “Once the repair is completed (including any necessary period for system learning or self-healing), the inducement override should automatically end, and such action thereafter results in the proper functioning of the device or element being repaired. If the fault that led to inducement remains active after the repair, the system should return to the induced state that existed prior to the repair.”
· To read EPA’s guidance on repairing emissions controls, click here.
EPA Guidance on Sensors for Emission Control Systems
On March 27, 2026, EPA issued further guidance on DEF systems regarding the use of Urea Quality Sensors.
EPA’s full announcement is available here. It reads in part:
“The agency’s new guidance makes clear that under existing regulations, manufacturers can stop inaccurate DEF system failures by removing traditional emission sensors, known as Urea Quality Sensors, and switching to nitrous oxide (NOx) sensors. EPA also affirms that approved NOx sensor-based software updates can be installed on existing engines without being treated as illegal tampering under the Clean Air Act.”
“Today’s announcement does not weaken or remove emissions standards.”
Manufacturers will be working with EPA and dealers to determine what solutions are possible for the equipment currently on the market and in the fields.
· To read EPA’s guidance on sensors, click here.
· EPA also has a DEF Sensor Guidance Fact Sheet, click here.