2021-later 121 Touring Softail Exhaust Oxygen Sensor Microcomputer OBD Computer Diagnostic Interface 1-to-2 Splitter Cabledescribe Oxygen sensor microcomputer Solved the problem of HD models (models with 3 exhaust sensors) changing the exhaust frequency and changing the fault code after 21 years. Directly plugged into the OEM OBD computer diagnostic socket, real time intervention ECU, feedback data, this set of data is also activated in real time, making the ECU receive and process data more accurately. Optimize the vehicle's air fuel ratio and improve the throttle