What is OBD2?
OBD or On Board Diagnostics is a vehicles built in diagnostic system. Have you ever notices a check engine light blinking on the dash board of your car? That is your car telling you that some thing is not right and you should visit a mechanic before it is too late. When you visit your mechanic, he connects a suitable scanner to a 16 pin connector in your car, read out all the DTC or Diagonostic Trouble Codes, understand the issue and fix it without taking your car apart.
CARB started including this standard in all cars that are manufactured after 1991 for emission control purposes. By 1994, it was made standard mandatory for all cars and by 1996 almost every other vehicles such as light trucks, medium duty vehicles and heavy duty vehicles started using this. Today, OBD2 is a standard in almost all vehicles.
How OBD2 work?
OBD2 standard is the most convenient method to access various data parameters from your vehicle. This standard uses a variety of PIDs or Parameter IDs which can be extracted from most of the regular vehicles using a suitable hardware. Which means, we can encoded form of various details such as engine RPM, pressure, fuel status, throttle position and other OBD2 data in real time using some key parameters. Decoding this data would require a database of conversion rules which may not be always available. So for hobbyist like us, accessing this data would require a little bit of reverse engineering. Here is a list of various Standardised PIDs.
We can connect an OBD2 data logger or a similar scanner to this cars 16 pin connector. Using this scanner we can input ‘request’ messages. The ECU accepts this message, process it returns a corresponding ‘response’ message back to the logger. This means that, you will not get output if you simply connect a passive, silent device to this port.
OBD2 Port Location in Honda City 2017
In most of the vehicles, this port is accessible from the drivers seat. In Honda City 2017 model, OBD2 Port is located under the dashboard of the drivers seat, above the clutch pedal of the vehicle.