A car is misfiring and has no DTC codes. What mode will assist the technician?

When diagnosing a car that is misfiring with no Diagnostic Trouble Codes (DTCs), using Mode 6 is particularly advantageous. Mode 6 on a scan tool provides access to the on-board diagnostics’ functional tests and monitor results that may not trigger a DTC despite indicating a malfunction.

This mode can reveal data such as misfire counts for each cylinder, efficiency of the catalytic converter, and other readiness monitors that evaluate the performance of various vehicle systems. By analyzing this information, the technician can pinpoint potential issues related to the misfire that are not reflected in the DTCs, allowing for a more comprehensive diagnosis.

Other modes, such as Mode 1 (live data), Mode 2 (freeze frame data), and Mode 3 (DTCs), have their own specific uses but may not provide the deeper insights necessary for identifying misfire issues when no codes are present. Mode 6 is designed specifically for advanced diagnostics, making it the most suitable choice in this scenario.