OBD stands for “On-Board Diagnostics.” It is a computer-based system originally designed to reduce emissions by monitoring the performance of major engine components.
Vehicle Compatibility Chart
All cars and light trucks built for sale in the United States after 1996 are required to be OBD-II compliant. The European Union OBD legislation is somewhat more complicated.
Communication protocols used in modern vehicles are incompatible with standard computer protocols (RS-232, USB, and so on). An OBD adapter (sometimes referred to as “vehicle interface adapter”) is an electronic device that allows a computer to access the vehicle network. It is similar in operation to a computer modem or a gateway, in that it translates messages from one protocol to another.
OBD-II offers a standard way to access many types of data, including:
Real-time parameters: RPM, speed, pedal position, spark advance, airflow rate, coolant temperature, etc.
Status of “Check Engine” light
Emission readiness status
Freeze frame: a “snapshot” of parameters at the time a trouble event has occurred.
Diagnostic trouble codes (DTCs).
Oxygen sensor test results
Vehicle Identification Number (VIN)
Number of ignition cycles
Number of miles driven with MIL on
There are 3 main jobs that the antifreeze in coolant performs to keep the engine coolant temperature normal:
1、It prevents the coolant from freezing during cold weather.
2、It raises the boiling temperature of the coolant to prevent overheating during hot weather.
3、It fights corrosion.