SAE J2534-1 and J2534-2
By Brian Herron
Standardizing diagnostics is not a new idea, it’s been a topic of discussion for as long
as I can remember. The one thing missing from widespread adoption in the past has been a proven and mature
standard for the diagnostics hardware. Now I think one has fallen into place by accident.
In this article I'm going to build a compelling case for a change in diagnostics. I'll first take a look at the
current state of the industry, and for opportunities for improvements that can benefit the OEM, supplier,
dealership, repair shop, and ultimately the customer.
These improvements not only save cost, but increase accessibility to the right tools needed to fix the car
correctly; anywhere, anytime.
Next I'll cover SAE J2534, a vehicle communications standard that many believe is the answer. I'll talk about
its history, intent, and what’s happening with it today.
After that I'll take a look at the Vision of using SAE J2534 as the standard diagnostics interface, and review
the use case. Lastly, we’ll summarize the benefits of standardizing diagnostics with J2534, cover some of most
common misconceptions, and outline a plan to move forward.
I think the first thing we need to do is step back and look at what happens during development of a next
generation tool. Typically Next Generation diagnostics programs start several years before they reach dealers
hands. Each OEM may be different, but generally the process is similar.
In the early stages, the OEM sends out RFQ’s for the diagnostics Hardware, and awards a contract. Sometimes the
contract is based on improving the vendor’s existing hardware platform, but more commonly the hardware is designed
from the ground up to meet the OEM’s requirements
In these scenarios, there must be a communications spec that PC application developers use to talk to the
hardware. When a SAE standard vehicle interface is not a requirement, not only does that preclude the opportunity
to use off-the-shelf hardware that may be cheaper and readily available, but it also adds a lot of work in
development to define and test the proprietary interface.
After contracts are awarded, development usually begins quickly. A PC Application for Diagnostics and a hardware
interface must be developed for the factory program. In addition to this effort, there must also be an application
developed to satisfy EPA, CARB, and EURO reprogramming requirements (J2534 or ISO22900)
What many are doing under today’s model is re-creating the wheel. On one hand we’re re-inventing hardware that
can be displaced by standardized hardware already in the market. The other major opportunity is to consolidate the
Diagnostics Application and J2534 regulatory program.
Once initial development is over, the product is released to dealers. There is a huge variation in cost from one
OEM to another, but the average for non-standardized hardware programs is between $2000 - $8000 for the tool
Around the same time, the OEM launches a J2534 diagnostics program from their website. This is required by the
EPA, CARB, and EURO regulations for emissions programming.
After the dealer roll out, the factory diagnostics tool is re-sold to the aftermarket. The aftermarket price is
typically higher than dealer cost for a number of reasons, most commonly because it is marked up and distributed
thru a different channel. Shops will have to decide if they can justify the cost of each OEM’s factory tool as most
cannot afford to buy them all.
During the program’s life, the OEM will have to support both the factory diagnostics program, and the J2534
application. Often the 2534 application will be maintained by separate code and will require separate updates every
time a new vehicle is launched or a bug is found. In other words, problems fixed during the normal course of
support for the factory diagnostics program may not make their way into the J2534 application used in the
At the end of the program, the whole development cycle will begin. In the past this would mean all new hardware.
In today’s model, the hardware needed just to perform factory diagnostics is expensive and out of reach for most
technicians in the aftermarket.
Looking at the current development cycle, it’s clear that there are some improvements that can be made. That’s
true for anything, nothing is perfect. But there needs to be a driving force to make it happen.
That driving factor here is COST! Everyone is worried about cost from the OEM and dealership to the aftermarket
technician and ultimately the CUSTOMER.
The OEM’s cost could be reduced by shortening development time, consolidating J2534 development with the factory
program, and picking from hardware solutions that are standardized and therefore more competitively priced. At the
same time, having a more affordable solution would allow more aftermarket shops to purchase it, leading to
increased diagnostics subscription revenue.
The Dealership and aftermarket repair shop both are always looking for lower cost fully functional tools.
Additionally, a lower cost to repair shops mean they can afford to buy more factory diagnostics tools, and have a
greater level of service to their customers.
Technicians want a single interface that works for multiple OEMs. Imagine if the same piece of hardware could be
used to service two different car brands. A standardized tool would allow them the ability to purchase tools from
multiple competing vendors, share the same tool for multiple OEM diagnostics solutions, and enjoy a longer life for
the hardware than a bespoke factory tool.
The customer benefits because they can take their car anywhere and have the car fixed with the right tools..
When your customer’s car is broken, they are likely to remember good and bad experiences the next time they are
shopping for a new car.
The key to reducing cost is adopting standards. Imagine a world where next-gen system could re-use the previous
generation of hardware.
As I said at the beginning of this article, this whole concept isn’t new. But until now there have been several
factors that have prevented widespread adoption of a standard vehicle communications interface.
Current generation tools were developed 10 years ago. What did the landscape look like then?
I think one of the main reasons for lack of VCI standardization has been the difference in vehicle networks. If
you walk back in time 10 years, which is when many OEMs developed their current generation diagnostics systems, it
was a completely different world. In the vehicles of 10 years ago, there may have been completely different
protocols used. CAN was still an emerging technology at that time and not present on most vehicles. Today, CAN is
on almost every vehicle and Tier1’s are supplying the same ECU’s to several different OEMs.
Looking back 10 years ago, the PC was just beginning to be introduced into the repair shop as an essential tool.
Today, I don’t think there’s a high end diagnostics shop in the country without one.
Another reason why the industry hasn’t standardized yet is the lack of standards. Again, you have to look back
5-10 years when today’s systems were being developed.
With all of these pieces falling into place, it’s not time to stop re-inventing the same thing. Why do 10 OEMs
all need to have their own proprietary VCI design? The same minimum set could satisfy all of them.
At this moment in time, we have reached a point where an existing SAE standard has become relevant for a new
The SAE standard J2534 was first written in 2002. It was originally developed as a standard for emissions
reprogramming, and was regulated by the EPA and CARB. here have been several revisions to the document to improve
the spec and increase testability of devices. Today, it has been proven as a viable standard and has had
The intent behind SAE J2534-1 was to offer aftermarket repair shops the ability to repair vehicles that required
software updates. The EPA Legislation required emissions programming on any 2004 or newer vehicle. Since release,
many OEM’s have offered J2534 emissions programming back to as early as 1994 vehicles.
There are three J2534 standards, J2534-1, J2534-2, and J2534-3
J2534-1 is the regulate standard. It was mandated for emissions programming and all OEMs must comply with it
J2534-2 is the optional set.
J2534-3 is the test against J2534-1
Since it’s publish date, every major OEM selling cars in the USA has been required to offer J2534-compliant
software for emission reprogramming.
In the aftermarket, where the standard was meant to help technicians, it has grown into an important tool. Over
the past 8 years technicians have learned what it is, how to use it, and it has become necessary for service at
shops that do no have the factory diagnostics solution.
SAE J2534 has also been included in EURO5/6 regulations, and can be used to fulfill the requirements for
J2534’s original intent was for vehicle reprogramming. IT was developed because there was no standard for
vehicle interfaces that could be utilized in the aftermarket. Once it was published, OEMs began to realize that the
same API used for diagnostics could also be used for reprogramming. This lead to OEMs developing their own internal
engineering applications that use SAE J2534 devices, and ultimately releasing diagnostics to the aftermarket over
SAE J2534. This was welcomed by technicians in the aftermarket that had already purchased SAE J2534 interfaces for
This activity also had a unique benefit to OEMs. They could now use the same software stream for diagnostics and
reprogramming, fulfilling the EPA/EURO J2534 requirements. This not only meets the requirements now, but pre-empts
future regulatory requirements
There is now a growing number of OEMs that are offering diagnostics over J2534. BMW was the first to offer some
factory diagnostics over J2534 from their web-based system. Toyota was next, and was the first to offer the entire
factory diagnostics solution, at the dealership AND in the aftermarket over SAE J2534. Several other OEMs have
announced plans to develop their next generation systems using SAE J2534.
Toyota is the first OEM to offer full factory diagnostics to the dealership and aftermarket using J2534.
Depending on the OEM requirements, J2534-1 may be complete enough to meet the full diagnostics requirements
without the use for J2534-2. I mentioned that Toyota implemented their entire factory diagnostics program over
J2534. This is a great example of an automaker that was able fit their entire program requirements within the
As the J2534 specification has matured, it was clear that some OEMs would need special features for service that
extend beyond what is written in J2534-1. The SAE committee wanted to create a way that OEMs could add in optional
features while still having them standardized and developed in the working committee.
That need lead to the creation of J2534-2. J2534-2 is not regulated or required by any legislation, but does
allow the OEM to expand J2534 to meet special requirements. OEMs have expanded it to support diagnostics, security
keys, and non-emissions module programming:
Some recent examples include: Honda added Diag-H, GM added UART and Single-wire CAN, VW added TP2.0. This
standard gives OEMs a mechanism to standardize and support new diagnostics protocols as technology advances.
There are some other intangible benefits of using SAE J2534 for diagnostics beyond just using standards.
As described earlier, the SAE J2534 standard is basically just passing data thru from the PC to the vehicle in a
standard way. The secrets and intellectual property relating to diagnostics, proprietary data, reprogramming, and
ECU security is all controlled from the PC application. This allows the OEMs to separate the hardware from their
intellectual property. There are no OEM secrets stored inside the hardware, and the OEM can maintain full control
of the PC Application where their secrets are held.
By moving the complexity into the application, it makes standardizing the hardware much easier. Now the hardware
vendor doesn’t need to keep track of OEM-specific diagnostics data and continually update their device. It also
removes cost because the device is simply passing messages back and forth.
Moving the IP to the PC application also allows the OEM to re-use more IP with each next generation tool because
the hardware is interchangeable and PC application code is often re-used.
The vision for the future is simply this: In the future, OEMs should write their factory diagnostics software to
use the SAE J2534 standard.
This enables them to have a single software stream for both the dealers and aftermarket that fulfills the
diagnostics and J2534 requirements.
In addition, OEM’s can release this to the aftermarket by charging a subscription fee from their website. This
allows the OEMs to bring in revenue directly from the technician without having to give profits and markup thru
Shops will enjoy this model because they will be about to use one J2534 tool for multiple OEMs. When using the
OEM software it will detect with J2534-1 and J2534-2 features are present on the tool and only features that can be
supported on their device.
Finally, this mass implementation of J2534 will drive down the cost of hardware to technicians. What costs
thousands of dollars per tool today will cost hundreds of dollars per tool in the future when it’s more widely
adopted. Toyota’s J2534 “Techstream Lite” tool the first J2534 tool to be adopted in dealerships, retails for $495
to technicians everywhere.