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DEF Sensor Simulator (DSS) - Modifying Emissions Systems Is Not Legal.

Copperhill Technologies Corporation provides the following products that some customers purchased to build a so-called "DEF Sensor Simulator:"

  1. Arduino-Based ECU Development Board With Dual CAN Bus Interface...
  2. Arduino-Due-Based ECU Development Board With Two CAN Bus Ports...
  3. Dual CAN Bus Interface For Arduino Due With Extended Power Range...
  4. Dual CAN Bus Interface For Arduino Due...

The vast majority of these purchases were triggered by a post in titled Good news! DEF head alternatives are coming.

Some users of our product developed a software to simulate a diesel engine's DEF sensor, and they published the software on Our product is a generic CAN Bus prototyping board whose functionality is defined by the software.


Copperhill Technologies Corporation neither participated in the development of the so-called "DEF Sensor Simulator" nor was it aware of its existence until September 14, 2021, i.e., when it engaged into online research after a customer pointed to the online post.

While the so-called "group of intrepid, like-minded, never-say-die RVers", a.k.a. "DEF sensor workaround group," is most probably a customer of ours, Copperhill Technologies Corporation was not aware of their activities. We most probably provided some technical support but, again, without any knowledge of the project's development result.

Copperhill Technologies Corporation advises against the installation of the so-called "DEF Sensor Simulator," because it does modify an emission system. The "DEF sensor simulator" tells the engine that all is well with the DEF system, even when it's not.

Copperhill Technologies Corporation will not provide technical support for such installation and is not responsible for any result of the installation.

Also, please be aware that one part of the "simulator," the Arduino Due, is specified for an operational temperature range of 0 to 50C, which translates into 32 to 122F. Depending on time of the year and current location, you can easily operate the device outside of its specified parameters.

Time Line

For the record, here is the time line of the events from our view:

  • On August 28, 2021, published an article "Good news! DEF head alternatives are coming."
  • On August 31, 2021, a customer contacted us to inquire the availability of our Arduino-Based ECU Development Board With Dual CAN Bus Interface with Extended Input Power Range of 7 VDC to 36 VDC. "I would like to specify it for a project that probably will generate at least a dozen orders in the next week."
  • In the following weeks, we noticed an uptick in orders for the part.
  • On September 12, 2021, published an article "It's out there - a DEF sensor workaround," showing our board in an enclosure.
  • On September 12, 2021, we received almost 100 orders for the part, and further orders are still flowing in.