Telematics unit unplugged, disconnected, or missing after body or audio work; Blown fuse or open circuit in the telematics module's constant or ignition power feed; Corroded, loose, or damaged connector at the telematics unit or an inline bus splice; Open or shorted CAN wiring between the telematics unit and the network it reports on; Failed telematics control module internal to the unit; Low battery voltage or poor ground causing the module to drop offline intermittently; Network configuration or module coding mismatch after a replacement or software update

DTC codes / U01xx · Lost communication with a control module / U0198

U0198Lost Communication With Telematic Control Module

Q: What does code U0198 mean?

Lost Communication With Telematic Control Module. U0198 is a network communication code indicating that one or more control modules have stopped receiving data from the Telematic Control Module (TCM), the telematics unit that handles connected services, emergency calling, and remote data transfer. The detecting module logs the fault when the expected periodic CAN (Controller Area Network) messages from the telematics unit fail to arrive within the timeout window, usually because the unit is unpowered, offline, or its bus wiring is compromised.

U0198 is a network communication code indicating that one or more control modules have stopped receiving data from the Telematic Control Module (TCM), the telematics unit that handles connected services, emergency calling, and remote data transfer. The detecting module logs the fault when the expected periodic CAN (Controller Area Network) messages from the telematics unit fail to arrive within the timeout window, usually because the unit is unpowered, offline, or its bus wiring is compromised.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

A stored U0198 with no drivability change and no warning light on many vehicles
Telematics, connected-services, or emergency-call features stop working or show an error
Remote start, remote lock, or app-based vehicle status functions become unavailable
A communication or network fault message displayed in the driver information center
Multiple unrelated modules logging U-codes at the same time if the bus is affected
Battery drain or a dead battery if the telematics unit fails to go to sleep

Common causes, most likely first

Telematics unit unplugged, disconnected, or missing after body or audio work
Blown fuse or open circuit in the telematics module's constant or ignition power feed
Corroded, loose, or damaged connector at the telematics unit or an inline bus splice
Open or shorted CAN wiring between the telematics unit and the network it reports on
Failed telematics control module internal to the unit
Low battery voltage or poor ground causing the module to drop offline intermittently
Network configuration or module coding mismatch after a replacement or software update

How to diagnose and fix it

Scan all modules and record every stored code to see whether the telematics unit is the only silent node
Verify battery voltage and check the fuse and ground serving the telematics control module
Inspect the module connector and harness for corrosion, pushed pins, and chafed or broken wires
Measure CAN bus resistance and check for shorts to ground or power on the communication pair
Confirm the module powers up and communicates on a known-good bench or with a substitute unit
Repair wiring or replace the telematics control module, then perform any required coding or configuration
Clear codes and road test through several key cycles to confirm the fault does not return

Why the telematics unit goes silent

This code frequently appears after stereo, alarm, or dash-camera installation work where the telematics connector was left unplugged or a bus splice was disturbed.
A telematics unit that stays awake and keeps transmitting can drain the battery, so a no-start complaint sometimes accompanies the communication code.
On many vehicles the telematics module sits on a dedicated sub-bus, so a single failed unit can set U-codes across several modules without affecting engine operation.
Replacing the telematics unit without transferring or programming its configuration can leave the new unit silent and reproduce the same code.
A weak battery or failing ground can make the module drop offline intermittently, so the code may clear on its own and return under load.

Can I keep driving with U0198?

The vehicle normally remains safe to drive because the telematics unit does not control engine, braking, or steering functions, but connected services and emergency calling may be unavailable. Avoid relying on automatic crash notification until the fault is repaired, and address any battery drain promptly.

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.