What is On Board Diagnostics : OBD Devices

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OBD stands for “On Board Diagnostics.” It is used to monitor major engine component performance. OBD was originally designed to control the emissions. In BS6 and Euro6 vehicles norms OBD-2 is mandatory. We suggest you also read this article on AdBlue Liquid.

  • Indicates engine check error in the instrument cluster if there is any problem with engine system.
  • Vehicle owners can use OBD device along with mobile application to monitor the vehicle.
  • Allows mechanic to diagnose the complete vehicle by diagnostic trouble codes (DTC)

All components that have an impact on emission or connected to ECU (engine control unit) should be monitored and diagnosed.

OBD system consists of ECU which gets input from sensors. As per input ECU control the engine functioning. 

In case of malfunctioning of any system or component. OBD sends error code to vehicle instrument cluster. Detailed error code can also be determined using Diagnostic Link Connector (DLC).

Types of OBD Devices

Two types of On-board diagnostics devices are available.


OBD1 was the first generation on-board diagnostic device. For that every vehicle manufacturer has their own proprietary connector and set of codes. For different vehicles mechanic has to buy different devices. OBD 1 scan tools were very costly and were out of reach of common man.


In 1990 SAE and ISO issued ECU and diagnostic scan tool communication protocols. After that it becomes mandatory for manufacturers to use standard diagnostic connector (SAE J1962) and communicate via standard communication protocol. 

OBD II Connector Pin Out

How to Read OBD2 Data

OBD2 supports various standard parameter IDs (PIDs) along with DTC codes. These PIDs helps in getting various data from vehicle such as speed, RPM, throttle position, fuel consumption etc.

Steps to read Vehicle Data 

Step-1 : Connect OBD2 device to vehicle. You can buy Bluetooth or Wi-Fi based OBD device from Amazon

Step-2 : Download OBD application for android/IOS/windows.

Step-3 : Connect application with OBD device

Enjoy the Live Data from your vehicle !!


To sum up, On Board Diagnostics (OBD) is used to diagnose vehicles. OBD2 devices are mandatory for BS6 or Euro6 vehicles.

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