Diagnosis Function
WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
ETACS-ECU checks if the data from the engine control module (ECM) is received via the CAN bus line. When ETACS-ECU cannot receive the ECM data, it stores the DTC No. B1731.