The U0197 code indicates that a control module on the vehicle network (typically the PCM, BCM, or instrument cluster) has lost communication with the Telephone Control Module. This module handles hands-free calling and Bluetooth connectivity, and the fault is usually due to a power, ground, or network wiring issue, or a failure within the telephone module itself.
Internal failure of the telephone module is the most common cause, often due to water intrusion, electrical overload, or component aging.
Damaged, corroded, or broken communication network wires between the module and the rest of the vehicle can interrupt data transfer.
Loose, backed-out, or corroded terminals in the module connector can cause intermittent or complete loss of communication.
A blown fuse, damaged wiring, or poor ground connection to the telephone module will prevent it from powering up and communicating.
Rarely, the module that sets the code (e.g., PCM) has an internal communication failure, but this is the least likely cause and should only be considered after all other possibilities are ruled out.
Yes, the vehicle remains drivable. The code only affects the hands-free phone system and does not impact engine, transmission, or safety functions.
It may illuminate the malfunction indicator lamp (MIL) on some vehicles, but often it only stores a code without turning on the light, since it is not an emissions-related fault.
Almost never. The telephone control module itself, its wiring, or power supply are the cause in the vast majority of cases. Replacing the PCM is a common misdiagnosis and should only be considered after exhaustive testing proves all other components are functional.
It is the electronic module that manages Bluetooth connectivity and hands-free calling. Its location varies by vehicle but is often behind the glove box, under a seat, or in the center console area.