1979 defines many PIDs, but manufacturers also define many more PIDs specific to their vehicles. Typically, an automotive technician will use PIDs with a dtc bus time table pdf tool connected to the vehicle’s OBD-II connector. There are 10 modes of operation described in the latest OBD-II standard SAE J1979. Vehicle manufacturers are not required to support all modes.
The table below shows the standard OBD-II PIDs as defined by SAE J1979. The expected response for each PID is given, along with information on how to translate the response into meaningful data. Again, not all vehicles will support all PIDs and there can be manufacturer-defined custom PIDs that are not defined in the OBD-II standard. Note that modes 1 and 2 are basically identical, except that Mode 1 provides current information, whereas Mode 2 provides a snapshot of the same data taken at the point when the last diagnostic trouble code was set. The exceptions are PID 01, which is only available in Mode 1, and PID 02, which is only available in Mode 2. If Mode 2 PID 02 returns zero, then there is no snapshot and all other Mode 2 data is meaningless.
When using Bit-Encoded-Notation, quantities like C4 means bit 4 from data byte C. Each bit is numerated from 0 to 7, so 7 is the most significant bit and 0 is the least significant bit. Mode 02 accepts the same PIDs as mode 01, with the same meaning, but information given is from when the freeze frame was created. You have to send the frame number in the data section of the message. DTC that caused freeze frame to be stored. Clears all stored trouble codes and turns the MIL off. VIN Message Count in PID 02.
Only for ISO 9141-2, ISO 14230-4 and SAE J1850. Calibration ID message count for PID 04. In-use performance tracking message count for PID 08 and 0B. In the formula column, letters A, B, C, etc. Some of the PIDs in the above table cannot be explained with a simple formula. A request for this PID returns 4 bytes of data. Each bit, from MSB to LSB, represents one of the next 32 PIDs and is giving information about if it is supported.
A request for this PID returns 4 bytes of data, labeled A B C and D. Bits A6 through A0 represent the number of diagnostic trouble codes currently flagged in the ECU. Number of confirmed emissions-related DTCs available for display. Here are the common bit B definitions, they are test based. The translation would be the ammonia sensor in the SCR catalyst. The first byte is always zero.
The second, third, and fourth bytes give information about the availability and completeness of certain on-board tests. A request for this PID will return 9 bytes of data. EGT bank 1, sensor 4 Supported? EGT bank 1, sensor 3 Supported? EGT bank 1, sensor 2 Supported? EGT bank 1, sensor 1 Supported?
The remaining bytes are 16 bit integers indicating the temperature in degrees Celsius in the range -40 to 6513. Only values for which the corresponding sensor is supported are meaningful. The same structure applies to PID 79, but values are for sensors of bank 2. A request for this mode returns a list of the DTCs that have been set. The list is encapsulated using the ISO 15765-2 protocol.
The table below shows the standard OBD, 09 is used to retrieve vehicle information. For a 1994 Corvette the implemented OBD, except that Mode 1 provides current information, vehicle manufacturers are not required to support all modes. Only for ISO 9141; the first byte is always zero. And fourth bytes give information about the availability and completeness of certain on, related diagnostic trouble codes detected during current or last completed driving cycle.