If you have been in the car repair industry for several decades you no doubt know that OBD II diagnostic systems evolved out of OBD I technology, but did you know that OBD 1.5 systems once existed? Younger technicians could be forgiven for not knowing this because these systems were only in use as a transitional measure between 1996 and 1999, which was when the implementation of OBD II systems became mandatory in the United States. However, the development of automotive technology is continuing apace, and while OBD II-compliant diagnostic systems have served both car manufacturers and the repair industry well, the technology is now fast approaching its limits in terms of its ability to keep track of faults in control systems that are getting more complex with each passing year. Thus, in this article, we will take a closer look at both the limitations of current OBD II technology, and what the future holds for on-board diagnostics, starting with-
You may not know this, but there are currently about 50 000 OBD II trouble codes in use worldwide. As we know, of these, a few thousand are generic codes that mean the same thing on all applications, while the rest are manufacturer specific codes that may or may not apply to all vehicles that are sold in all jurisdictions or markets. You may have seen abbreviations that contain the letters "OBD" in different places, and it is these abbreviations that refer to codes that are largely unique to one or more specific markets. Here are some examples-
EOBD2
This is mostly used as a marketing term that some manufacturers use to identify faults that occur in systems and/or features on their vehicles that are neither described nor defined in either or both the OBD II or EOBD standards. In this case, the "E" identifies the codes as "Enhanced Codes".
EOBD
This stands for European On-board Diagnostics and the term refers to codes that are used on vehicles that are produced in Europe. In this market, all petrol vehicles made from January 2001, and diesel vehicles made from 2003 must be equipped with EOBD-compliant diagnostic systems to monitor exhaust emissions.
JOBD
This is an OBD II version that is used on vehicles sold in the Japanese domestic market.
ADR 79/01 & 79/02 (Australian OBD standard)
In the context of the Australian market, the OBD II version that is defined by the Australian Design Rule 79/01 is arguably the most important version of OBD II diagnostics to consider. This rule states (inter alia) the following-
Scope
1.1 This vehicle standard prescribes the exhaust and evaporative emissions requirements for light vehicles to reduce air pollution.
Applicability and Implementation
2.1 This vehicle standard is applicable to all M1 and N1 category vehicles with a GVM less than or equal to 3.5 tonnes, in accordance with the requirements of clause 1.1 of Appendix A and as provided in clause 2.2.
2.2 This vehicle standard applies:
2.2.1 From 1 January 2005 in relation to new model vehicles with an engine that operates on petrol, liquefied petroleum gas or natural gas produced on or after 1 January 2005;
2.2.2 From 1 January 2006 in relation to vehicles with an engine that operates on petrol, liquefied petroleum gas or natural gas, produced on or after 1 January 2006, other than new model vehicles referred to in clause 2.2.1;
2.2.3 From 1 January 2006 in relation to new model vehicles with an engine that operates on diesel produced on or after 1 January 2006; and
2.2.4 From 1 January 2007 in relation to vehicles with an engine that operates on diesel, produced on or after 1 January 2007, other than new model vehicles referred to in clause 2.2.3.
Source: https://www.legislation.gov.au/Details/F2005L04080
In practice, the Australian standard is equivalent to the OBD II SAE J-2012 standard in all respects, including its technical implementation and the use of a data link connector that complies with the SAE J-1962 standard, which describes the 16-pin data link connector that we all know.
While the above may be of interest to some readers, it should be noted that the various standards that define OBD II technology allow car manufacturers in different markets to adapt the operating parameters of systems such as ABS, Stability Control, Active Suspension and others to match the operation of these systems to local driving conditions. For instance, the winding, twisting roads of Japan and much of Europe places greater demands on systems like Active Suspension control than the largely straight and smooth roads in the North American market would place on a similar system in a similar vehicle.
As a result, some systems, and particularly safety systems are programmed differently in different markets but note that this is not the same as saying that the technical implementation of OBD II technology differs between markets in meaningful ways. In translation, this means that the different programming of some systems between markets does not present a departure from the basic definitions of OBD II fault codes, nor does it represent an evolution of how OBD II systems track and report faults.
However, what is evolving is how the increasing numbers and complexity of monitoring and control systems, such as ADAS (Advanced Driver Assist Systems) and telematics systems are integrated both into each other and into increasing numbers of ever-more powerful control modules even on entry and mid-level vehicles. As a practical matter, all of these additional systems and their associated control systems and modules are adding layer upon layer of complexity to modern automotive diagnostics, and it is fast becoming apparent that many, if not most current OBD II fault codes can no longer convey sufficient diagnostic information, which brings us to-
This image shows the Mercedes-Benz EQ Silver Arrow Electric Intelligence Car, a conceptual design that was first shown at the 2018 Paris Motor Show. Although this actual vehicle will almost certainly not enter production, inevitably, much of the new technology it contains will eventually filter down into more mundane production models. This is important from a diagnostic perspective, since many current OBD II fault codes (as we know and understand them today), will almost certainly not contain enough diagnostic information to allow for the definitive diagnosis and repair of critical systems on future generations of particularly, high-end and exotic vehicles.
In its simplest form, the problem is this: in current OBD II fault code constructions, only the last two digits convey any useful diagnostic information. Let us take generic trouble code P0001 as a random example- in this case, the third digit points us to the fuel and air metering system, but it is only the "01" part of the code that contains any useful diagnostic information, in the sense that "01" indicates an open circuit in the Fuel Volume Regulator's control circuitry.
There are many other possible examples, but the point is that as control modules have evolved, both their computing and storage capacities have increased greatly. As a result of this, all the organisations* that are involved in maintaining the various OBD II standards have been collaborating in continually updating the basic SAE J-2012 standard to reflect the increasing complexity of modern vehicles.
* These organisations include the Society of Automotive Engineers (SAE), the International Organisation for Standardisation (ISO), the Institute of Electrical and Electronics Engineers (IEEE), and all major car manufacturers.
Nonetheless, despite efforts to keep the basic OBD II standards up to date, the above organisations have realised that advances in automotive electronics have outstripped their collective ability to devise, describe, and authorise new trouble codes. What was needed was a new way to construct fault codes, and as a result, the responsible organisations have published an annexe to the SAE J-2012 standard, which is known as SAE J-2012DA*.
* This annexe, which comes in the form of an Excel spreadsheet, is available from the SAE’s website. Note though that all other relevant and associated standards are also available at prices of several hundred dollars each, which brings us to the new-
Essentially, the SAE J-2012DA standard adds two additional digits to the end of a trouble code, thus creating trouble codes with seven digits. Here is an example; the ubiquitous P0300 code (Random Multiple Misfires Detected), as it applies to the 2019 Toyota Tacoma-
In this instance, the P0300 random multiple misfire code is split into three (sub) codes, these being-
We all know that diagnosing random misfire codes can be tricky, and even more so on the many late-model vehicles that feature multiple spark ignition systems and fuel injection events that can be split into five or six separate injections. Therefore, the aim of adding an additional layer of diagnostic information in the form of the last two digits is to identify the system or part of a system that is most likely to contain the fault that had set the main P0300 code.
In the above example, the crankshaft position sensor is still used to detect the variations in the crankshaft’s rotational speed that are caused by misfires. However, the misfire detection system now also uses an additional and very complex algorithm to determine something known as the EWMA (Estimated Weighted Moving Average) of the crankshaft to calculate both the effect of misfires on emissions, and the likelihood that damage to the catalytic converter(s) might occur as the result of the misfire(s).
Thus, by creating codes-within-codes, car manufacturers are able to provide us with valuable insights not only into the most likely cause(s) of the issue but also into which system the fault is located, as well as insights into the most likely effect a particular 7-digit code will have on expensive emission control system components.
There are, however, some disadvantages to 7-digit codes, such as the fact that many of the code readers we now use in the independent repair industry might not be able to extract 7-digit codes. Another major disadvantage is that unless we purchase the SAE J-2012DA annexe (and its future updates) for several hundred dollars each time an update is released, we might not always have access to accurate descriptions of the new 7-digit codes. This is particularly important in respect of manufacturer-specific 7-digit codes, and especially so given the fact that it can be almost impossible for independent workshops to obtain any technical information from manufacturers.
How these issues will be resolved remains to be seen, but as if the learning curve that will come with 7-digit trouble codes is not troublesome enough, there has been much talk about a further new development in OBD diagnostics, which brings us to -
There is not so much a debate going on about whether or not OBD III will ever become a reality, as there is misinformation, speculation, and conspiracy theories being bandied about, which can make it difficult and confusing to separate fact from fiction. Here are the facts, or at least, the facts that are currently available-
There is ample evidence to prove that the basic framework to make OBD III work already exists, but the truth is that OBD III has much less to do with on-board fault detection, than it has to do with reporting emissions-related issues on vehicles to both regulatory and law enforcement authorities via a network of ground stations.
Essentially, this system will have the ability to use currently available onboard telematics systems to report defects in emission control systems to the authorities, which could mean several things to drivers of such vehicles. For instance, a driver or car owner could receive a fine through the mail, or be directed to report to an emissions testing centre within a pacified time, or as some conspiracy theories maintain, have his vehicle forced into a limp mode by remote control, which will persist until the fault is corrected.
Sounds like the stuff nightmares are made of, doesn’t it? Well, here is another fact: this system has been shown to work, but only in the state of California where it is facing several legal challenges. One such challenge involves the gross invasion of privacy of drivers/car owners, and another involves both the definition of the term “regulatory bodies”, and just how far these bodies will be allowed to go in terms of enforcing emissions regulations.
Similar legal challenges will inevitably arise in other markets and jurisdictions. Nevertheless, while it is not for this writer to anticipate the outcome(s) of these challenges, this writer can without fear of being contradicted say that the possibility of OBD III in its current form being introduced into any market is exceedingly slim to none, which leaves us with this-
Current definitions and interpretations of OBD II trouble codes will simply not provide enough diagnostic information to make definitive diagnoses of even common issues on the next generation of light vehicles. Therefore, the introduction of 7-digit trouble codes represents not only a real and significant advance in modern automotive diagnostics but also a major departure from OBD II diagnostics as we know it today.
