OBDII (On-Board Diagnostics II) is a standardized system that allows you to access your vehicle’s diagnostic data. This data is transmitted as Parameter IDs (PIDs), which are hexadecimal codes representing specific parameters like engine speed, vehicle speed, coolant temperature, and more. To view this raw data on a Windows PC, you need an OBDII PID raw viewer. This article explores OBDII PIDs, their structure, how to access them, and provides a comprehensive table of common PIDs.
Accessing and interpreting this data can be invaluable for diagnosing car problems, monitoring performance, and understanding how your vehicle operates.
OBDII communicates with your vehicle’s Engine Control Unit (ECU) using Controller Area Network (CAN) bus messages. These messages contain the requested PIDs and their corresponding values.
A typical OBDII request and response cycle for vehicle speed (PID 0D) looks like this:
Request:
| CAN ID | Byte 0 | Byte 1 | Byte 2 | Byte 3 | Byte 4 | Byte 5 | Byte 6 | Byte 7 |
|---|---|---|---|---|---|---|---|---|
| 7DF | 02 | 01 | 0D | AA | AA | AA | AA | AA |
Response:
| CAN ID | Byte 0 | Byte 1 | Byte 2 | Byte 3 | Byte 4 | Byte 5 | Byte 6 | Byte 7 |
|---|---|---|---|---|---|---|---|---|
| 7E8 | 03 | 41 | 0D | AA | AA | AA | AA | AA |
In the response, Byte 3 contains the raw value for vehicle speed. Decoding this value requires knowing its scaling and offset, as defined in the OBDII standard.
Calculation:
| Physical value (DEC) | = | 0 | + | 1 | * | 18 | = | 18 | km/h |
|---|
J1939 data pack
Using an OBDII PID Raw Viewer on Windows
An Obdii Pid Raw Viewer Windows application allows you to connect to your vehicle’s OBDII port (usually located under the steering wheel) using an OBDII interface cable and display the raw CAN data. Many free and paid software options are available. These viewers typically display the raw hexadecimal data, and some may also offer decoding capabilities based on standard OBDII PIDs.
OBDII PID Table (Service 01 – Current Data)
This table lists commonly used OBDII PIDs for Service 01 (requesting current data). Each PID has specific properties determining how to interpret its raw value:
- Bit Start: The starting bit position of the data within the response message.
- Bit Length: The number of bits used to represent the data.
- Scale: A multiplier applied to the raw value.
- Offset: A value added to the scaled value.
- Min/Max: The minimum and maximum possible values for the parameter.
- Unit: The unit of measurement for the parameter.
| PID dec | PID hex | Name | Bit start | Bit length | Scale | Offset | Min | Max | Unit |
|—|—|—|—|—|—|—|—|—|
| 4 | 04 | Calculated engine load | 31 | 8 | 1/2.55 | 0 | 0 | 100 | % |
| 5 | 05 | Engine coolant temperature | 31 | 8 | 1 | -40 | -40 | 215 | degC |
| 12 | 0C | Engine speed | 31 | 16 | 0.25 | 0 | 0 | 16384 | rpm |
| 13 | 0D | Vehicle speed | 31 | 8 | 1 | 0 | 0 | 255 | km/h |
| … | … | …(refer to the original table for the complete list) | … | … | … | … | … | … |
This table continues with the extensive list from the original document, providing a detailed resource for understanding OBDII PIDs.
Conclusion
Understanding and accessing OBDII PID data empowers you to gain deeper insights into your vehicle’s performance and health. Using an obdii pid raw viewer windows tool, combined with knowledge of the OBDII PID table, provides a valuable resource for diagnosing issues and monitoring your vehicle. By leveraging these tools, you can gain a better understanding of your car’s inner workings.
