Data rate 1.2 to 10.4 kBaud Message may contain up to 255 bytes in the data field ISO 15765 CAN (250 kbit/s or 500 kbit/s). The CAN protocol was developed by Bosch for automotive and industrial control. Unlike other OBD protocols, variants are widely used outside of the automotive industry. While it did not meet the OBD-II requirements for U.S. vehicles prior to 2003, as of 2008 all vehicles sold in the US are required to implement CAN as one of their signaling protocols. pin 6: CAN High pin 14: CAN Low All OBD-II pinouts use the same connector, but different pins are used with the exception of pin 4 (battery ground) and pin 16 (battery positive). OBD-II diagnostic data available OBD-II provides access to data from the engine control unit (ECU) and offers a valuable source of information when troubleshooting problems inside a 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 formula to convert raw OBD-II output to meaningful diagnostic units, see OBD-II PIDs. Manufacturers are not required to implement all PIDs listed in J1979 and they are allowed to include proprietary PIDs that are not listed. The PID request and data retrieval system gives access to real time performance data as well as flagged DTCs. For a list of generic OBD-II DTCs suggested by the SAE, see Table of OBD-II Codes. Individual manufacturers often enhance the OBD-II code set with additional proprietary DTCs. Mode of operation/OBD services Here is a basic introduction to the OBD communication protocol according to ISO 15031. In SAE J1979 these "modes" were renamed to "services", starting in 2003. Service / Mode $01 is used to identify what powertrain information is available to the scan tool. Service / Mode $02 displays Freeze Frame data. Service / Mode $03 lists the emission-related "confirmed" diagnostic trouble codes stored. It displays exact numeric, 4 digit codes identifying the faults. Service / Mode $04 is used to clear emission-related diagnostic information. This includes clearing the stored pending/confirmed DTCs and Freeze Frame data. Service / Mode $05 displays the oxygen sensor monitor screen and the test results gathered about the oxygen sensor.