OBD2 PID Request and Response

In an OBD2 (On-Board Diagnostics 2) system, PID (Parameter ID) request and response are used to access real-time data from various sensors and systems within a vehicle. Here’s how the PID request and response process works:

Request for PID Data

A diagnostic tool or scanner sends a PID request to the vehicle’s onboard computer system (ECU). The request specifies the desired PID, which corresponds to a particular data parameter, such as engine RPM, vehicle speed, or coolant temperature.

Response from the ECU

The ECU responds to the PID request by providing the data associated with the requested PID. The response typically includes the current value of the parameter, such as the engine RPM or temperature.

Interpretation of Data

The diagnostic tool or scanner interprets the data received from the ECU and presents it in a human-readable format. This allows technicians and vehicle owners to monitor the vehicle’s performance and identify any issues or anomalies.

For example, if you request PID 0x0C, which corresponds to engine RPM, the ECU will respond with the current engine RPM in revolutions per minute.

PID requests and responses play a crucial role in OBD2 diagnostics, providing real-time data that can be used for monitoring, troubleshooting, and maintenance of the vehicle. The specific PIDs supported by a vehicle can vary, and the response format may differ depending on the make and model of the vehicle and the OBD2 protocol being used.

External Reference: Refer to the csselectronics OBD2 PID table for detailed information on PID request and response frames.