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U0198 — Lost Communication Telematic Control Module

Generic OBD-II · all makesNetwork / communication

The U0198 code indicates that the vehicle's network cannot communicate with the Telematics Control Module (TCM). This loss of communication can affect infotainment, connectivity, and vehicle status functions.

Symptoms

What causes it — most likely first

1. Faulty TCM module

The TCM itself may have failed due to internal electronic faults or solder joint issues.

2. Poor electrical connection or corrosion

Loose pins, water intrusion, or corroded terminals in the TCM harness can interrupt signal transmission.

3. CAN bus wiring damage or short

Frayed wires, abrasion, or a short to ground or voltage on the CAN lines will break communication.

4. Faulty Body Control Module or other network node

A malfunctioning module on the same CAN network can cause loss of message traffic to the TCM.

5. PCM communication failure (rare)

In some vehicle designs the PCM shares the communication network; a severe PCM fault could indirectly cause loss of TCM communication, but this is uncommon.

How it's diagnosed

  1. Connect a scan tool and confirm the presence of U0198 while noting any additional codes.
  2. Visually inspect the TCM connector and wiring for corrosion, damage, or loose pins.
  3. Measure CAN‑high and CAN‑low voltages at the TCM pins to verify proper voltage levels.
  4. Perform a continuity and resistance test on the CAN bus wiring between modules.
  5. If wiring is intact, test the TCM for proper response using a scan tool or bench test; replace the TCM if it fails.
  6. If the TCM is functional, inspect other modules on the network and consider wiring harness replacement if needed.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make
Related codesU0190 — Lost Communication Digital Disc PlayerU0191 — Lost Communication TelevisionU0192 — Lost Communication Personal ComputerU0193 — Lost Communication Digital Audio ContrU0194 — Lost Communication Digital Audio ContrU0195 — Lost Communication Subscription Entert

Frequently asked

Does U0198 always mean the TCM must be replaced?

No. Most often the issue is a wiring fault or a poor connection rather than a failed TCM.

Can a faulty PCM cause U0198?

Only in rare cases where the PCM shares the communication network; usually the PCM is not the primary cause.

Will clearing the code fix the problem?

Clearing the code will only remove the stored DTC; the underlying communication issue will remain until repaired.

Is this a safety‑critical fault?

U0198 primarily affects convenience features; however, if it triggers limp‑mode or disables critical vehicle information, it should be addressed promptly.