The challenge lies in fully understanding the data beyond the basic Diagnostic Trouble Codes (DTCs). Specifically, interpreting the detail records associated with these codes and finding comprehensive DTC text descriptions are key hurdles. Let’s delve into an example to illustrate this.
Consider a scenario where a scan tool retrieves a DTC, and along with it, a detail record. For instance, an error code reported as “20 04 00 08” might translate to a VAG specific code 2098176. Online research and tools like CarPort suggest this relates to “Quick battery charging (DC) Charge stn., initialization error, error_initialisation_fast_charging.”
Now, examining the extended data associated with this, we might see a sequence like: “19 06 20 04 00 FF 59 06 20 04 00 08 01 02 03 02 58 00 05 8E 00 00 1F A8 FA E3 7A 1D E5 00 01 1D EF 00 00 00 00 00 00 00 00 00 00 00 00 04 01“. Breaking this down, “59 06” could be PID + 0x40. The core error code “20 04 00 08” is present again. Bytes “01 02 03” might represent masks, with “02” possibly indicating error priority and “03” error frequency. “02 58” could be a reset counter, and “00 05 8E” potentially the mileage when the error occurred. “1F A8 FA E3” is highly likely a timestamp, representing date and time. “7A” might act as a delimiter. Following this, “1D E5 00 01” could be a PID related to Chademo version, with two data bytes at the time of the error. Similarly, “1D EF 00 00 00 00 00 00 00 00 00 00 00 00 04 01” might be PID for DC charging process data with 14 data bytes at the time of the fault.
While this interpretation provides a structure, decoding the timestamp and definitively sourcing DTC text descriptions remain open questions. Service documentation, like erWin for VAG vehicles, might hold some answers, although even comprehensive databases like VCDS sometimes encounter unknown error codes. Further investigation and community collaboration are crucial to fully decode and utilize the wealth of information contained within extended OBD2 diagnostic data accessed via commands like 22f1a5 Obd2.
