What mode should be accessed to check if the ECM has saved a permanent record of a failure after clearing a trouble code?

The correct mode to access for checking if the Engine Control Module (ECM) has saved a permanent record of a failure after clearing a trouble code is Mode 10. This mode is specifically designed to read permanent diagnostic trouble codes (DTCs). Permanent DTCs are those that are stored in the ECM even after a trouble code has been cleared. They indicate that a malfunction was present and may help technicians assess whether the issue has been resolved or if it remains.

In contrast, other modes such as Mode 8, Mode 9, and Mode 11 serve different purposes. Mode 8 is used primarily for vehicle-specific diagnostic functions, such as special tests for components or systems. Mode 9 is utilized to report vehicle information, including the VIN and calibration ID. Mode 11 provides access to non-permanent DTCs that can be cleared and don’t necessarily indicate a permanent failure status.

Understanding the specific functions of each mode is essential for effective diagnostics, and knowing that Mode 10 is the one focused on permanent records helps technicians not only in troubleshooting but also in ensuring compliance with emissions regulations.