What does OBD II covered?

[xbomb2]

Guys : I am new here. Can anybody tell me what kinds of info can I extract out from OBDII reading. I

[Nitrous]

OBD-II (OBD two) is the latest industry standard, which was introduced on 1996 vehicle models. It provides monitoring of nearly all engine controls, and also some other parts of the vehicle (chassis, body, etc.).

The most useful part of OBD to most drivers is the ability to read information from the vehicle. You can read trouble codes, and even monitor real-time statistics such as RPM, vehicle speed, etc from inside the vehicle.

The SAE J1979 standard defines a method for requesting various diagnostic data and a list of standard parameters that might be available from the ECU. The various parameters that are available are addressed by "parameter identification numbers" or PIDs which are defined in J1979. For a list of basic PIDs, their definitions, and the formulae to convert raw OBD-II output to meaningful diagnostic units

There are nine modes of operation:

Show current data
Show freeze frame data
Show stored trouble codes
Clear trouble codes and stored values
Test results, oxygen sensors
Test results, non-continuously monitored
Show pending trouble codes
Special control mode
Request vehicle information

Good Luck and happy reading.

[xbomb2]

Is ther anyway to get ODOMETR reading ?
also I can understand RPM. How do you convert to Speed?

[Nitrous]

You're getting away from OBDII but:

Formula for MPH
MPH = Tire Radius / 168 X Engine RPM / Diff ratio / Gear ratio
The above does not calculate torque converter slippage which can be higher than 200RPM.