Blown fuse or poor power/ground connection at the telephone control module; Damaged or corroded wiring in the CAN bus circuit between the telephone module and the gateway or PCM; Failed telephone control module itself, often due to internal electronic failure; Loose or disconnected connector at the telephone module or at an intermediate splice point; Network communication disruption caused by another module on the same bus segment shorting or drawing down the line; Software or configuration mismatch after battery replacement or module replacement without proper programming

DTC codes / U01xx · Lost communication with a control module / U0197

U0197Lost Communication With Telephone Control Module

Q: What does code U0197 mean?

Lost Communication With Telephone Control Module. U0197 is a generic network communication code indicating that the engine control module or another primary module has lost contact with the telephone control module over the vehicle's controller area network bus. The computer detects this when it sends periodic messages to the telephone module and receives no response within the expected time window, often setting the code after multiple failed attempts.

U0197 is a generic network communication code indicating that the engine control module or another primary module has lost contact with the telephone control module over the vehicle's controller area network bus. The computer detects this when it sends periodic messages to the telephone module and receives no response within the expected time window, often setting the code after multiple failed attempts.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

Illumination of the check engine light or service vehicle soon message on the dashboard
Often no symptoms besides the warning light, with all phone and infotainment features working normally
Bluetooth pairing failures or dropped calls if the telephone module is truly offline
Inability to use hands-free calling, voice commands, or emergency call functions
Other unrelated warning lights or communication codes if the fault lies on a shared network segment

Common causes, most likely first

Blown fuse or poor power/ground connection at the telephone control module
Damaged or corroded wiring in the CAN bus circuit between the telephone module and the gateway or PCM
Failed telephone control module itself, often due to internal electronic failure
Loose or disconnected connector at the telephone module or at an intermediate splice point
Network communication disruption caused by another module on the same bus segment shorting or drawing down the line
Software or configuration mismatch after battery replacement or module replacement without proper programming

How to diagnose and fix it

Verify battery voltage and check all fuses related to the telephone module and infotainment system
Inspect the telephone module connector for corrosion, loose pins, or water intrusion
Perform a voltage drop test on the power and ground circuits at the telephone module
Use a scan tool to check for other communication codes and confirm whether the telephone module appears on the network at all
Measure CAN bus resistance and check for shorts to ground or battery voltage on the bus lines
If the module is unresponsive but power and ground are good, substitute a known-good module or perform a module ping test with a factory-level scan tool
After repair, clear codes and verify communication is restored by cycling the ignition and rechecking for U0197

What most technicians overlook with U0197

A dead telephone module often does not disable the vehicle, so many drivers ignore the code until hands-free or emergency calling is needed.
The telephone module may share a fuse or ground with the radio or amplifier, so a blown fuse can set U0197 along with audio codes.
After replacing a telephone module, some vehicles require configuration or pairing with the gateway module, and skipping this step will immediately reset U0197.
A weak or failing battery can cause intermittent communication loss on the CAN bus, setting U0197 without any hard fault in the telephone module.
Water intrusion into the trunk or under-seat area where the telephone module is mounted is a common hidden cause of corrosion and communication failure.

Can I keep driving with U0197?

The vehicle remains safe to drive because the telephone module is not part of the powertrain or safety systems, but you should avoid relying on hands-free calling or automatic emergency call features until the fault is repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.