U0197

Universal

Lost Communication With Telephone 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
Low Severity

The vehicle is not receiving expected messages from the telephone control module over its communication network. Depending on the vehicle, this module may support phone, hands-free, or connected communication features. The code does not by itself prove the module has failed; a power, wiring, connector, network, or software issue can also interrupt communication.

Report an error with this code

⚠️ Before You Begin (Safety First)

This code alone does not usually mean the vehicle is unsafe to drive. If phone or emergency-call features are unavailable, do not rely on them; use another way to call for help. If other warning lights or system problems appear, have the vehicle assessed promptly.

Common Symptoms

  • Phone or hands-free functions may be unavailable if they depend on the telephone control module.
  • Connected communication features may stop working or show a related warning, depending on vehicle equipment.
  • A warning or stored code may appear without an obvious change in driving; some vehicles may show no noticeable symptoms.
  • Other communication-related features may be affected if the underlying network problem involves additional modules.

Common Causes

  • A loose, damaged, corroded, or poorly connected telephone-module connector or wiring may interrupt communication.
  • A loss of module power or ground can prevent it from responding on the vehicle network.
  • A fault elsewhere on the communication network may interfere with messages to or from the module.
  • The telephone control module may have an internal fault, but testing is needed to distinguish this from wiring or power problems.
  • A software or configuration issue, or recent electrical work, may affect module communication.

Diagnostic Steps

  1. Note which phone, hands-free, or connected features are not working and whether other warning lights or electrical issues are present; this helps establish whether the problem is isolated.
  2. Use the vehicle handbook to identify any related fuses, then check them safely as directed. Replace a fuse only with the specified type and rating; if it fails again, seek diagnosis.
  3. With the vehicle off, visually inspect accessible wiring and connectors related to the telephone system for obvious damage, looseness, or corrosion. Do not force connectors or dismantle trim to reach hidden components.
  4. If you have a suitable scan tool, read codes from all available modules and record them before clearing anything. Multiple communication codes can point to a broader network or power issue.
  5. If the code returns, the module is inaccessible to the scan tool, or wiring checks require disassembly or electrical testing, arrange vehicle-specific diagnosis rather than replacing the module based on the code alone.

When to Call a Professional

A technician can scan all modules to see whether this is an isolated communication loss or part of a wider network problem. Useful checks include confirming the telephone module has the correct power and ground, inspecting its connectors and wiring, and testing network communication using vehicle-specific service information. Module replacement or programming should follow diagnosis, not be assumed from this code alone.

Compare component listings

Confirm diagnosis and vehicle fitment before buying. A listing does not prove that a part needs replacement. We may earn a commission from qualifying purchases.

Search Amazon Search eBay

Commonly Asked Questions

Does U0197 prove that the telephone control module needs replacement?

No. It reports lost communication, which can result from a module fault, but also from a power, ground, connector, wiring, network, or software problem.

Can I keep driving with this code?

The code alone does not usually prevent driving. Phone or connected features may not work, and any emergency-call feature that depends on the module may be unavailable.

Why might there be no symptoms?

Some vehicles can store a communication code without showing a noticeable symptom, or the affected telephone feature may not be in use.

What helps distinguish a module fault from a network problem?

Scanning all modules and checking the telephone module's power, ground, connectors, wiring, and network communication helps narrow down the cause. The exact tests depend on the vehicle.

Browse Available Code Guides

Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.