DEF systems in modern diesel engines are crucial to reducing Nitrous Oxide (NOx) emissions and protecting the environment. The DEF system combines software, hardware, and DEF fluid that enable this critical task. Unfortunately, a flood of failures has recently affected one of the elements of the DEF system called the DEF sensor. The origins of this “DEF pandemic” are unknown, but the failures may be related to heat, poor design, or a high failure rate of the internal semiconductor.
The reason doesn’t matter, as the consequences of DEF sensor failure to the driver and passengers are significant. First, this failure causes an instant and progressive slowing of the engine function called “derate,” even though the primary process of the emissions systems continues to operate. Derate strands of vehicles and their occupants on the side of the road, or worse, force them to go slower than traffic, which is equally dangerous.
Replacement parts are not readily available. Covid-19 disruptions in the supply chain for semiconductors have exacerbated the availability problem. As of the fall of 2020, industry analysts forecast this chip shortage to last into 2022. As a result, many diesel equipment users are sidelined for days, weeks, or months while waiting for replacement parts. The irony is that despite the danger and the inconvenience, the affected emissions system is not broken. Instead, the DEF sensor stops reporting accurate information, so the ECM (Electronic Control Module) makes an incorrect assumption that the emissions system is broken and begins to derate the user. The classic symptom of the failed sensors is a Check Engine light (and possibly other indicators) with three fault codes followed by derate. Click here for details on the fault codes. Being unnecessarily derated in a diesel-powered vehicle is dangerous to its occupants.
DEF Head Alternatives Are Coming
Federally mandated DEF (Diesel Exhaust Fluid) monitoring systems have been stranding RVers. It’s a problem with plenty of dynamics, including why the sensors fail, a shortage of microchips, and rounding out with recalcitrant industry and government officials. In any event, we have stacks of emails from upset RVers who cannot or are afraid to use their rigs because of the issue. But thanks to persistent and innovative RVers, two DEF head alternatives are on the horizon. Read more...
DEF Sensor Workaround
If you’ve been following the saga of stranded RVers, it reads like a Shakespeare tragedy. But unlike the outcomes for Cleopatra or Macbeth, some of you may find light at the end of the story. In two months, a group of intrepid, like-minded, never-say-die RVers has devised a solution that may get their RVs on the road again. From all appearances, it’s a great DEF sensor workaround. Read more...
About the DEF Sensor Simulator
The DEF System Simulator (DSS) is a hardware/software solution a user can build. It is made of inexpensive, readily available parts to assist derated users in being able to perform a temporary fix as soon as a DEF sensor failure occurs and safely operate their vehicle until a repair can be obtained. Upon installation, the DSS removes (and follows a set of procedures contained in the documentation) the derate condition and will permit its users to reach a repair facility safely with full engine power. Read more...
DEF Sensor Simulator - Quick Build
Since the original DSS solution was published in September of 2021, the team has been looking at alternative hardware and software options. This page briefly describes and links to the build instructions for all the variants developed to date. The team has deemed the solution in the Recommended section to be the most viable current option considering factors such as price, size, parts availability, ease of programming, etc. Any build options are still possible solutions and provide opportunities during supply chain shortages. Read more...
DEF Sensor Emulator Firmware and Assembly Manual
This repository contains the compiled Arduino Due sketch for emulating a Diesel Exhaust Fluid (DEF) head and instructions for assembling an emulator. This code is compiled for the Arduino DUE, UNO and ATMega2560. Read more...
Arduino Due with Dual CAN Bus Interface (Original Build)
The original project uses an Arduino DUE board with a separate CAN board add-on. Programming the board is not difficult but somewhat more complex than the RP2040 and requires a Windows system. However, it does not require any soldering.
The introduction of 500 Kbps (see SAE J1939/14) as an alternative to 250 Kbps, required clarifications on how to solve problems that come with incorporating devices supporting different baud rate settings in the same network. One solution comes with automatic baud rate detection. The SAE J1939/16 document outlines the methods used to detect the baud rate [...]
The JCOM1939 Monitor Software is ideal for monitoring, recording, analyzing, and simulating SAE J1939 data traffic. The system works in combination with our SAE J1939 gateways. This comprehensive and easy-to-use, easy-to-understand Windows software displays not only SAE J1939 data traffic but also scans the network, simulates an ECU (incl. full node address negotiation features), and responds [...]
Like many other businesses, we have to deal with the global shortage of electronic components. For instance, the NXP LPC 17xx processors we used for our SAE J1939 gateways and the starter kit are not available at this time. Even worse, there is no reliable information if/when production resumes. This situation forced us to rethink [...]
The following is an update on our activities regarding our development of an SAE J1939 data recorder. The development affects two of our devices, the SAE J1939 Gateway Module With USB Port, RTC, MicroSD Memory Card and the SAE J1939 Gateway And Data Logger With Real-Time Clock. Both gateways are supported by our free-of-charge jCOM1939 Monitor, an SAE J1939 [...]
Warwick Control Technologies has released a development kit that enables users to simulate Classical CAN, CAN FD, and LIN devices and networks. It also supports the simulation of SAE J1939, NMEA 2000, and CANopen devices and networks. The kit comes with the Kvaser Hybrid Pro two-channel interface to test Classical CAN, CAN FD, and LIN systems through [...]
Copperhill Technologies offers various SAE J1939 data traffic simulation and monitoring devices that also support data logging. All of these devices are based on industrial-strength hardware, operating under an extended temperature range of -40 to +85 Celsius and making them suitable for operation within offroad vehicles and lab test conditions. The JCOM series of SAE J1939 [...]
The JCOM.J939.USB-X SAE J1939 Processor board is an extended version of our popular JCOM.J9139.USB-B SAE J1939 ECU Simulator Board With USB Port. The most significant difference is that the -X version supports a USB transfer rate of up to 480 Mbps, allowing higher data throughput. The onboard real-time clock supports the timestamping of the SAE J1939 [...]
Our JCOM.J1939 Starter Kit And Network Simulator is designed to allow the experienced engineer as well as the beginner to experiment with SAE J1939 data communication without the need of connecting to a real-world SAE J1939 network, i.e. a diesel engine. It may sound obvious, but in order to establish a network, you need at least two [...]
The following represents an update on our current development activities, in this case the jCOM.J1939 Programmable Data Traffic Simulator (a first prototype is shown in the image to the left).In short, the plan is that the device is being set up by means of a Windows software and then runs the programmed PGNs (Parameter Group [...]