Does OBD2 Work On Diesel?

Onboard diagnostic (OBD) systems were first developed and optimized for gasoline engines, but they are now widely used in diesel engines as well. All diesel-powered vehicles with a gross vehicle weight rating (GVWR) of less than 14,000 pounds must now comply with OBDII criteria for monitoring the functioning of their pollution control systems as of the 2007 model year.

“But nothing can be considered to be certain in this world except death and taxes,” wrote Benjamin Franklin. If Franklin could see into the future, he would almost certainly have added ever-stricter pollution control measures to his list. Standards have only been tougher since the California Air Resources Board (CARB) first started regulating pollutants that had a negative influence on the state’s air quality, and technology has been constantly developing to meet these new difficulties.

Diesel automobiles are no strangers to OBD systems. In 1994, CARB and the US Environmental Protection Agency (EPA) mandated OBDII for light-duty diesel vehicles (GVWR less than 8,500 pounds) beginning in 1997. California legislation mandated OBDII compliance for all medium-duty trucks (8,500 to 14,000 pounds GVWR), including gasoline and diesel-powered, starting in 1997. However, the EPA did not immediately follow California’s lead in this area, allowing federal vehicles with GVWRs of 8,500 to 14,000 pounds to be exempt from OBDII compliance. The government required the use of onboard diagnostic devices, although they did not have to be as comprehensive as those required for California automobiles.

It became evident that improvements were required over time, and beginning in 2004, OBDII was phased into the EPA’s “heavy-duty” class (8,500- to 14,000-pound GVWR). As of 2007, all vehicles in this weight class sold in the United States must be OBDII compliant.


Since 1997, federal diesel-powered pickups and vans have been offered with an OBDII exemption for a number of model years. Onboard diagnostics were necessary on these vehicles, but they did not have to be as extensive as their OBDII equivalents. What was the difference between the federal versions and OBDII automobiles marketed in California and other states that embraced California emission standards?

The majority of the variances were in individual Powertrain Control Module (PCM) calibrations, as both versions used the same serial data bus, data connection connector, and basic PCM software. The federal models had fewer supported monitors, but both used the same general and enhanced scan tool modes. With a quick visual assessment, it would be difficult to discern any significant differences.

The glow plug system was an exception in some cars, where various hardware may be employed to regulate and monitor glow plug performance. Glow plug monitors were not necessary in federal vehicles, but they had to be able to diagnose a faulty glow plug, set a Diagnostic Trouble Code (DTC), and turn on the Malfunction Indicator Light (MIL) correspondingly in California vehicles. The federal (OBDI) calibration for a 2003 Ford 6.0 liter turbodiesel is detailed in the sidebar. Overall, the MIL is far less likely to be illuminated in federal vehicles than it is in California models that are OBDII-compliant.

Diesel Engine Monitors

The operation of the supported monitors is critical to the operations of an OBDII-compliant emission control system. All components and systems that play a substantial part in the vehicle’s emissions production must be monitored with OBDII, and one or more of the following tests must be performed:

Electrical tests are carried out. Sensors and actuators are checked for continuity, short circuits, signal out-of-range, and other issues.

Tests of rationalism. deciding whether the data supplied makes sense in light of additional data input in the case of sensors

Tests that are functional. Identifying whether a device is appropriately responding to computer commands.

Active or passive methods can be used to conduct functional tests. During normal operation, passive testing involves waiting for an actuator to get an instruction from the vehicle’s computer and then searching for sensory data that indicates appropriate operation. In active testing, the computer takes control of the actuator solely for the purpose of testing.

A number of monitors, similar to those used in gasoline engines, are employed in diesel engines. Comprehensive component monitoring and exhaust gas recirculation are just two examples. There’s also a misfire monitor, but it’s only active when the computer is inactive. Components that were once only found in gasoline engines are increasingly being utilised in diesel engines to provide monitoring duties.

The Mass Air Flow (MAF) sensor, which is now utilized with diesel engines to monitor the operation of the Exhaust Gas Recirculation (EGR) system, is an excellent example of this. Total airflow into the engine is recorded when the EGR valve is closed, and an associated decline in airflow is expected as the EGR valve opens, much as it is in gasoline applications.

In some circumstances, this new value is compared to a speed-density computation based on the engine’s rpm signal and a Manifold Absolute Pressure (MAP) sensor. The effective EGR gas flow is the difference between the two readings, and it is compared to what the vehicle’s computer requested to establish whether a defect exists in the system.

While diesel engines have some monitors in common with gasoline engines, they also have several that are specific to diesels. The EGR cooler monitor is one example. The exhaust gas recirculation system is critical for reducing nitrogen oxide (NOx) emissions from modern diesel engines. To accomplish the intended effect, very high rates of EGR flow are required, and the EGR gases must be cooled.

The Ford 6.4 liter Powerstroke, for example, performs this purpose by connecting two liquid-cooled EGR coolers in series. Because the EGR cooler has such a large impact on vehicle emissions, it requires an OBDII monitor to ensure proper operation. Two temperature sensors are utilized to monitor the EGR cooler operation on the 6.4 liter Powerstroke: one on the exhaust manifold as it flows into the EGR system, and one near the EGR valve itself.

The PCM may assess the efficiency of the coolers by looking for a temperature difference between the inlet and outlet sensors with the EGR valve open when the EGR cooler monitor is running. A first failure of this test would result in a pending code and a freeze frame, whereas a second failure would result in a DTC and the MIL being illuminated.

The Diesel Oxidation Catalyst (DOC) efficiency monitor is another example of a monitor that is specific to diesel engines. The DOC is used to oxidize hydrocarbon (HC) and carbon monoxide (CO) pollutants, as well as specific Particulate Matter fractions (PM). Even in California OBDII applications, DOCs have been employed in diesel-powered pickups and vans in the past, but their operation was not monitored. Since the 2007 model year (particularly, vehicles constructed after January 1, 2007), this has changed, and these vehicles must now include a catalyst efficiency monitor in their OBD approach.

While oxygen sensors are used to measure the effectiveness of catalysts in gasoline engines, exhaust gas temperature sensors are most commonly used to determine the efficiency of DOCs. Typically, this monitor will be on while the Diesel Particulate Filter (DPF), which is positioned downstream of the DOC, is actively regenerating. When the exhaust valve is open, a small amount of fuel is injected. When this post-injection fuel enters the DOC, the temperature of the exhaust gas rises as the catalyst oxidizes the surplus HC. At the DOC input, the temperature of the exhaust gases is measured and compared to the values at the outlet.

The amount of fuel injected for DPF regeneration determines the minimal predicted temperature increase. A DTC is set and the MIL is illuminated if the exhaust gas temperature does not rise to the anticipated minimum.

Closed Loop Operation

We can expect closed-loop operating in diesel engines in the not-too-distant future. New piezo-resistive sensors have been created that can be used with a glow plug in the same device. Because the glow plug can reach the combustion chambers of the engine, it is now able to assess cylinder pressures during a combustion event and make fuel control modifications based on this information. Because the ability to limit peak pressures in the combustion chamber also limits NOx generation, this is a big step forward in diesel emission management.

The scan tool for diagnosing diesel engine fuel and emission control system issues can also be supplemented with cylinder pressure data that can be used to perform new and more complex monitors, making it increasingly useful for diagnosing diesel engine fuel and emission control system difficulties.

Do OBD2 scanners work on all cars?

Most OBD2 scanners and auto code readers aren’t compatible with all vehicles. If you’re looking for an OBD2 scanner or car code reader, make sure it’ll work with your specific make and model before purchasing.

What vehicles are OBD-II compliant?

After January 1, 1996, all vehicles and light trucks made and sold in the United States have to be equipped with OBD II. In general, this means that all 1996 model year vehicles and light trucks, even if constructed in late 1995, are compatible.

Does Tesla have odb2?

A conventional OBD2 port is not available on the Tesla Model 3 and Model Y. Instead, a console connector is located in the vehicle’s rear seat, where an OBD2 tool or device can be plugged in using a Tesla OBD2 adapter.

A diagnostic port cable adapter and an ELM327 or STN1110 compliant OBD2 tool or device are required for the Tesla Model 3 and Y’s diagnostic port. The OBDLink LX or MX Bluetooth devices are the most often utilized OBD2 tools for Tesla Models. We highly propose our own OHP OBD2 Adapter for Tesla Model 3 & Y 2019-2020 Build for the diagnostic port cable adapter.

The Tesla Model 3 and Y have security safeguards that make it difficult to customize or hack the vehicle’s system and vital functions. As a result, utilizing diagnostic apps or software to connect to the vehicle’s diagnostic port will only allow users to access and display the vehicle’s live data. The Scan My Tesla app (Android and iOS) and the TM-Spy app are the major apps used to display live data (Android and iOS).

– Temperature sensor readings from the battery pack 16 pairs of readings (coolant inlet/outlet temperatures)

– The number of miles driven on the current battery pack (if you swapped packs the pack mileage will be different for the dash display)

The majority of the information displayed by the apps came from the Tesla Model 3 community, which identified and compiled the Tesla Model 3’s CAN bus IDs and data. The document can be found here.

Do JDM cars have OBD2?

Is my automobile compatible with Car Scanner? I get a lot of e-mails with this query, and the answer isn’t as simple as it appears.

All cars that comply with the international standards SAE J1979 and ISO 15031-5, often known as the OBD-II standard, are compatible with the Car Scanner.

It is, in reality, a set of criteria and conditions that must be satisfied by an automobile in order to detect defects related to potential environmental harm. Yes, the OBDII standard is primarily intended to protect the environment, but it also aids in the diagnosis of other issues.

The OBDII standard specifies specifications for the car’s hardware and software.

The inclusion of a standard D-shaped diagnostic connector with 16 pins is a must for us in terms of hardware requirements. The ELM327 adapter is connected to this connector.

Software requirements include obligatory support for one of the following protocols:

In addition, the standard governs the list of possible inquiries as well as the interpretation of their responses. A “010C” request, for example, is required to determine the current engine speed. Each byte in the response corresponds to 0.25 revolutions per minute.

A frequent misperception is that this standard applies to all automobiles manufactured after 1996. No, it’s not the case. I’ve tested a number of cars while working on a Car Scanner. Thousands more users who had written to me have tested even more autos. As a result, I’ve gathered some information about OBDII standard support.

The OBDII standard became mandatory in the United States in 1996 for all cars built for the domestic market.

So, how about the European Union? Only since 2001 has the OBDII standard (or European OBD – EOBD) been mandated for all fuel (petrol) vehicles. It has been required for all diesel vehicles sold in the EU since 2003.

The standard was made mandatory for all automobiles manufactured for the Chinese market in 2008.

Please note that we are not discussing vehicles manufactured in the United States, the European Union, China, or Australia. We’re talking about automobiles made for the United States, the European Union, and China.

But what about the automobile business in Japan? This standard is not obligatory in Japan. As a result, the majority of RHD cars built for the Japanese market do not accept the OBDII standard. When the Japanese design a vehicle for the US, EU, or Chinese market, they include support for the OBDII standard.

Where does the rest of the world stand? I don’t have data for all nations, however OBDII support isn’t required in the majority of them. When OBDII support isn’t required in your nation, it’s merely your car manufacturer’s goodwill. Or maybe not…

As a result, certain automobiles built for the European market before to 2001 support the OBDII standard – the automaker has elected to include it for all markets.

However, there are numerous instances where a car manufacturer has included the OBDII D-shaped connector from the American version in a European modification, but has installed a different electronic control unit (ECU) or firmware that does not support OBDII. Although the connector is present, the software does not support the OBDII standard.

It’s crucial to understand the difference between OBDII diagnostics and diagnostics using the vehicle manufacturer’s proprietary procedures.

The OBDII standard allows for universal diagnosis. The ELM327 chip is unconcerned about the vehicle to which it is linked. The standard governs communication methods, parameters, and sensors. The car’s self-reported list of supported parameters.

Most cars, however, enable sophisticated diagnostics in “factory” mode in addition to OBDII diagnostics.

Most of the time, the ELM327 can’t be used in “manufacturer” mode. Although many automobile manufacturers have integrated advanced diagnostic functionality into the OBDII protocol, the ELM327 adaptor can theoretically be used to access these functions (like Toyota, Ford, etc.).

The fundamental issue here is that you have no idea where those functions are situated or what they tell you or do. I presume you don’t want to turn off the third injector by accident? All advanced diagnostics-related dealer papers have been closed. Depending on the car manufacturer, access to paperwork for these processes can cost anywhere from $10,000 to $100,000.

Do semi trucks use obd2?

At DriveELD, we’ve discovered that drivers are frequently unaware of the sort of diagnostic port installed in their vehicle. We wanted to show you a couple other ways to find out. To begin with, there are three types of diagnostic ports: 6-pin (J1708), 9-pin (J1939), and OBDII. OBDII ports are used by light and medium-duty trucks, while 6-pin and 9-pin ports are used by heavy-duty trucks. Volvo and Mack trucks equipped with OBDII ports need a heavier-duty cable.

What is JPRO?

JPRO Professional is the industry’s most popular in-shop diagnostic and repair software. JPRO helps technicians detect and correct all issues on a truck by covering all makes and models and providing industry-leading bi-directional controls.

Customers can add NextStep Repair, a collection of repair manuals and step-by-step instructions for resolving fault or symptom-based issues across all engine makes and models, to JPRO software, which contains an incorporated troubleshooting module called Fault Guidance.