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Toyota OBD — Toyota On-Board Diagnostics and What It Can Be Used For

July 13, 2022

A Toyota OBD scanner can also serve well in everyday life when the vehicle shows no signs of problems. In this article, we want to explain the usefulness and purpose of a Toyota OBD scanner. Aside from being able to quickly diagnose your Toyota, a Toyota OBD scanner can provide many other benefits.

The history of Toyota OBD

Toyota Motor cooperation belongs to the largest car manufacturer in the world. In 2020, the vehicle manufacturer produced over 9.53 million vehicles and has since been considered the world’s largest automaker. The Japanese company is considered the world’s twelfth largest publicly traded stock company and employs nearly 400,000 people. Toyota’s vehicles are manufactured at twelve Japanese plants and 51 locations in 26 countries. Until 2020, the company founded by Toyoda Kiichiro and Toyoda Eiji in 1937 was considered the most valuable automotive brand in the world.

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The Toyota A1 and the GG Trucks was introduced in 1935. The model AA was first delivered from 1936. The actual automobile manufacturer Toyota was founded, to be exact, on August 28, 1937. By the way, the family name Toyoda was not used for the company to allow the founders to separate their work life from their private life.

The first Toyota cars were offered in Switzerland starting in 1967. In Germany, sales began in 1970. In 2004, Toyota’s market share was already 5% in Germany and over 12% worldwide. Due to the great success of Toyota vehicles, the Japanese manufacturer introduced the luxury brand Lexus for the American and European markets, which became the best-selling luxury car brand in the USA.

Due to U.S. environmental protection laws, Toyota began equipping vehicles with an OBD1 port as early as 1989. Then, starting in 1996, the Toyota OB2 became standard on all models.

Why was the Toyota OBD introduced?

Due to air pollution problems in California’s major cities, the California Air Resource Board (CARB) introduced new emissions regulations in the 1980s. The Environmental Protection Agency quickly realized that it was not enough just to check the applicable exhaust emission regulations at the time of registration, but that the exhaust emission values also had to be monitored over the entire service life of the vehicles. This is why the OBD1 standard was adopted in 1988, which stipulates that vehicles must have their own electronic self-monitoring system for the exhaust system.

On-board diagnostics (OBD) was introduced for light commercial vehicles and vehicles with a gross vehicle weight of 7.5 t in two steps:

OBD-I – all vehicles sold in California beginning in 1991 were required to be equipped with the first version’s on-board diagnostics.

OBD-II – the stricter OBD regulation was gradually introduced in 1994. Since 1996, all new cars and trucks sold in California using gasoline as well as alternative fuels must be equipped with OBD-II. All vehicles with diesel engines, cars and trucks, must also meet OBD-II requirements starting in 1997.

Basically, the OBD1 system is limited to monitoring a few emission-relevant components. This system had not yet been calibrated to a specific emission level. The Toyota OBD2 system was designed to address these shortcomings and make it more user-friendly for service technicians. The on-board diagnostics function is integrated into the vehicles’ on-board computers and enables monitoring of all components that can influence emissions behavior. Each component must be checked by a diagnostic routine to determine if it is functioning properly. When a problem or malfunction is detected, a warning light on the vehicle’s instrument panel shall be turned on to warn the driver. This warning light usually displays the phrase “Check Engine” or Service Engine Soon” . The Toyota OPB also stores important information about the detected malfunctions so that an automotive technician can quickly find and fix the problem.

The Toyota OBD system in Europe

The European on-board diagnostics regulation EOBD is the equivalent of the OBD-II. The “E” in this case stands for “Enhanced”. Basically, however, both are based on the same signal protocol and the SAE J1962 diagnostic connector.

Sometimes the term “EOBD2” is also used, but this is only used for marketing reasons and does not represent a different class. It is not part of the OBD or EOBD standard.

Can I use the Toyota OBD to diagnose only the exhaust system?

With the OBD standard, the California Environmental Protection Agency primarily wanted to create a way to test the various components and thus the function of the emission control system. In the last two decades, however, the proportion of electronic components in motor vehicles has risen sharply. Toyota OBD diagnostic connector has turned out to be a very convenient way to check the complete electronic system of a vehicle. One of the most important prerequisites for this is the CAN bus system.

The CAN bus and the Toyota OBD

The Controller Area Network or CAN bus is a robust bus standard for motor vehicles that allows control units in a vehicle to be interconnected without a host computer. This is a message-based protocol originally developed for multiplex cabling in motor vehicles. Data is transferred serially to this bus system and the device with the highest priority can pass on messages while the other control devices hold back. All control units can receive and send messages.

In 1983, Robert Bosch GmbH began to develop the CAN bus system. It was then presented at a conference in the USA in 1986. In 1991, the first production vehicle, a Mercedes-Benz W140, with a CAN-based bus system was introduced.

Why is the CAN bus so important for OBD?

Up to 100 different control units are now used in modern vehicles. They can all communicate with each other and receive data to perform their specific functions. The OBD diagnostic connector is also part of the CAN bus system. All ECUs can therefore be queried via it and the on-board diagnostics can be used. Thus, the OBD standard has also prevailed over the CAN bus, which uses only two cables for communication between the various control units. In addition, the CAN bus is one of five protocols used in the OBD2 standard for vehicle diagnostics.

What can be interrogated with a Toyota OBD scanner?

Although individual sensors can also be queried via the OBD diagnostic connector, it is primarily the fault codes that are of interest. Each control unit is responsible for different tasks and can generate error codes in case of malfunctions or problems.

If an error or incorrect data is detected by a control unit, it is first stored in the debouncing counter. If the error occurs again within a specified period of time or during the next query, an error poop is generated and stored in the error memory. If the error does not occur again, it will be deleted from the debouncing counter. Depending on which error has been detected, the warning light in the dashboard is also activated.

Through a Toyota OBD scanner, these error codes can be queried, as well as cleared if necessary. Since there is a connection between all ECUs through the CAN bus, the Toyota OBD scanner can also be used to diagnose the other ECUs.

What do the error codes look like in the Toyota OBD?

Each Toyota OBD error code consists of five characters. The first character is always a letter, followed by four numbers. The letter continuously refers to the queried system, which is broken down as follows:

Since automobile manufacturers also have the option of developing their own fault codes, the second character in a fault code can be used to indicate whether it is a standard fault code (0) or a manufacturer-specific code (1).

The other digits then refer to the respective lower system, and can define the exact error code with the last two digits.

The standard trouble codes have all been set in the DTC (Data Trouble Code) and can thus be read with the Toyota OBD scanner. In Europe, the DTC has also been defined in the SAE J2012 and ISO 15031-6 standards.

Toyota also uses the DTC to set its own fault codes. Here is an excerpt of the error codes defined by Toyota:

P1300 Ignition circuit fault – No. 1.

P1310 Ignition circuit malfunction – No. 2.

P1335 No signal from crankshaft position sensor – engine running.

P1349 VVT system.

P1400 Under throttle position sensor

P1401 Range/performance problem of the under throttle sensor.

P1405 Turbo pressure sensor circuit.

P1406 Range/performance problem of the turbo pressure sensor.

P1410 EGR valve position sensor – circuit defective.

P1411 EGR valve position sensor circuit range/power.

P1500 Circuit for starter motor signal

P1510 Boost pressure control circuit

P1511 Low boost pressure

P1512 Boost pressure high

P1520 Brake light switch signal malfunction.

What do the different modes of Toyota OBD mean?

To enable trouble-free reading of fault codes with the Toyota OBD scanner, 10 different test modes have been defined. They can be used to call up all the functions of the on-board diagnostics:

  1. Vehicle-specific diagnostic data
    In this mode, data values and sensor data can be queried in real time. This function can also be used to query the “Readiness Code”, which displays all components installed in the vehicle in a 12-digit binary code.
  2. Fault Environment Data or Freeze Frame Data
    When the control units detect a fault and the warning light is activated, freeze frame data is acquired and stored for this purpose. At the time of the fault, they are a snapshot of the data from the components and sensors. These can help diagnose the defect, as all data can be displayed from the time the fault occurred.
  3. Permanent error codes that lead to the warning lamp lighting up
    In this function it is possible to recall all the defects that led to activation of the warning lamp in the dashboard. Vehicle manufacturers also have the option of defining their own fault codes that can cause the warning light to be triggered and are stored in this memory area.
  4. Deleting the emission-relevant error codes and fault environment data
    In this mode, all emission-relevant data can be deleted with the Porsche OBD scanner. This includes the error memory and the freeze frame data. Under certain circumstances, the manufacturer-specific error messages can also be deleted here.
  5. Lambda probe monitoring
    This function can be used to query the continuous monitoring of the lambda sensor and display the test results.
  6. Non-continuously monitored systems
    This area stores error messages that did not activate the warning lamp. The errors have been detected but have no systemic consequences to activate the warning light.
  7. Continuously monitored systems, warning light not active
    All data that triggered an error message only in one work cycle and were not sufficient to store an error code can be queried in this mode. They can help identify potential sources of error.
  8. Manufacturer-specific test functions
    In this mode, manufacturers can include their own test functions. However, this function is not usually used by European brands.
  9. Vehicle identification
    In this mode, it is possible to retrieve important data from the vehicle, which is stored in various control units. This includes, among other things, the vehicle identification number (VIN) and brand- and type-specific information.

What can I do with a Toyota OBD scanner?

A Toyota OBD scanner offers the possibility to check the onboard electronics in your vehicle. It can access all control units and evaluate all essential data. Even though much of the data collected by ECUs is not important to the vehicle owner, it can be used to perform important analyses. The best example of this is checking the mileage of a vehicle. Many used cars are sold with manipulated mileage these days to fetch higher prices. The Carly OBD Scanner can be used to read the data from all ECUs. This detects whether the mileage of a used car has been manipulated.

Another important advantage of a Toyota OBD scanner is its ability to read fault codes, clear them and thus quickly identify problems. In addition, general data can be determined, such as the different temperatures of the fluid in the vehicle or the fuel consumption.

Reading fault codes can be very expensive in garages, which means that the investment in the Carly OBD scanner pays for itself very quickly. If the vehicle is diagnosed with the Carly OBD scanner only once a month, the investment will pay off in less than four months. More importantly, always feel good about using a safe vehicle with no fault codes indicating current or future problems.

What Toyota OBD scanners are available?

A Toyota OBD scanner can be very useful if he vehicle owner wants to know constantly about the condition of his vehicle. It also offers the possibility of detecting errors early and thus avoiding greater damage.

We would like to introduce you to some of the different types of Toyota OBD scanners that can be used for reading the data and trouble codes.


Toyota OBD - the Toyota on-board diagnostics and what it can be used for.
Toyota OBD Handheld

Handheld Toyota OBD scanners can be handheld, as the name suggests. They have their own monitor on which the read-out data can be displayed. Various buttons can be used to control the different modes of the OBD and thus query various data. The operation of these devices is relatively complicated and in most cases requires special training.


Toyota also sold a handheld Toyota OBD scanner to authorized repairers until 2005. The device was supplied with many different interfaces and cables so that it was also possible to diagnose vehicles up to the early 1990s. The device was very expensive, so many workshops decided not to buy it because of the cost. The original Toyota OBD scanner is also not suitable for private individuals due to its high price.


Original Toyota OBD Scanner

Toyota OBD - the Toyota on-board diagnostics and what it can be used for.
Original Toyota OBD Scanner

Starting in 2006, Toyota will deliver the “Toyota Techstream” to its authorized workshops. This is a Toyota OBD scanner that connects to the OBD diagnostic connector via software on a laptop. The Toyota Toughbook was offered in a full version and in a “light” version, which can only diagnose vehicles from 1996 onwards. All both devices come with a 1-year subscription for updates to all new Toyota models. For all both devices several 1000 € have to be paid. For this reason, they are not suitable for individuals who are looking for a Toyota OBD scanner to diagnose their vehicle themselves.


Modern Mobile OBD Scanner

A much more practical and convenient solution is offered by Carly OBD Scanner. This Toyota OBD scanner completely eliminates the need for complex technology. Only one adapter is sold, which is plugged into the Toyota OBD diagnostic connector, and a

Bluetooth connection with a smartphone or tablet. This leverages the processing power of modern mobile devices to enable an increased, more user-friendly condition. Carly OBD Scanner can be used even by people who have no experience with diagnostic equipment. Shortly after the Carly OBD scanner has read the data from the vehicle, a traffic light system is provided to indicate the condition of the car. Green indicates that no problems were found. Yellow is displayed when problems have been found but do not endanger the safety of the occupants or the vehicle. Red indicates that there are serious problems that should be corrected as soon as possible.

Even though the Carly OBD scanner was primarily designed to be very easy to use, the software offers the same capabilities as the other Toyota OBD scanners. If desired, all functions can be queried individually and even type-specific adjustments can be made, if these are possible. The user of a Carly OBD scanner can even subscribe to additional packages that can be used to test other vehicles. The Carly Smart Mechanic has capabilities that provide detailed repair instructions and diagrams that normally only authorized repair shop technicians can use.

Toyota OBD Conclusion

Since the California Environmental Protection Agency developed the OBD standard for checking exhaust systems, on-board diagnostics have come a long way in recent years. Meanwhile, even private individuals can use the Carly Toyota OBD Scanner to make in-depth diagnoses of a vehicle and even check whether a vehicle’s mileage has been tampered with. For this reason, a Toyota OBD scanner can be a very important tool nowadays to quickly and accurately diagnose the condition of a vehicle.