U0198

Universal

Lost Communication With Telematic Control Module

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

A vehicle controller has detected that it is not receiving expected messages from the telematics control module. This module may support connected services such as remote features or emergency communication, depending on the vehicle. The code identifies a communication problem, not proof that the module itself has failed.

Report an error with this code

⚠️ Before You Begin (Safety First)

Connected or emergency-call features may be unavailable. Do not rely on them until checked; use a phone or another means to call for help. If the vehicle also has warning lights, drivability problems, or other communication faults, have it assessed promptly and stop driving if it is unsafe to control.

Common Symptoms

  • Remote or connected services may not work if they depend on the telematics module.
  • An emergency-call or vehicle-assistance feature may be unavailable, depending on the vehicle's equipment.
  • A warning or message about connected services may appear.
  • There may be no noticeable symptoms if the affected function is not in use or the communication fault is intermittent.

Common Causes

  • A temporary interruption in communication between the telematics module and another vehicle controller.
  • A problem with power or ground reaching the telematics module.
  • A loose, damaged, or corroded connector or wiring connection.
  • A fault elsewhere on the vehicle communication network.
  • An internal telematics module fault, which should be considered only after its circuits and network connections are checked.

Diagnostic Steps

  1. Note any connected-service or emergency-call warnings and whether remote features have stopped working; this helps establish what functions are affected.
  2. Check the owner's manual for relevant fuses and inspect only those that are safely accessible. Replace a fuse only with the specified type and rating; if it blows again, seek diagnosis.
  3. With the vehicle off, visually inspect accessible telematics-related connectors and wiring for looseness or visible damage. Do not unplug connectors unless the vehicle-specific instructions say it is safe.
  4. Check whether other electrical or communication warnings are present. Multiple affected systems can point to a broader power or network issue rather than an isolated module problem.
  5. Have a qualified technician scan all modules and test the relevant power, ground, wiring, and network circuits before replacing a component.

When to Call a Professional

Scan all vehicle modules and compare their communication faults to determine whether the issue is isolated to the telematics module or part of a wider network or power problem. A technician can check the module's power, ground, connectors, wiring, and network communication using vehicle-specific service information and suitable diagnostic equipment before recommending parts.

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Commonly Asked Questions

Does U0198 prove the telematics control module is bad?

No. The code reports lost communication, which can result from a power, ground, connector, wiring, or network problem as well as an internal module fault.

Can I keep driving with this code?

The code alone does not establish that the vehicle is unsafe to drive. Connected or emergency-call features may be unavailable. If other warnings or drivability problems are present, have the vehicle checked promptly and do not drive if it feels unsafe.

Why might there be no obvious symptoms?

The fault may affect only connected services, or it may be intermittent. Some vehicles do not show a noticeable warning for every loss of communication.

Should I replace the telematics module?

Not based on this code alone. Diagnosis should first check the module's power and ground, its connectors and wiring, and communication on the vehicle network.

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