AutoCodes – Mercury – U0198 Mercury

U0198 Mercury Code - Lost Communication With Telematic Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Telematic Control Module, Telematic Control Module harness is open or shorted, Telematic Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: U0198 Mercury indicates Lost Communication With Telematic Control Module.
Common causes: Common causes include Faulty Telematic Control Module, Telematic Control Module harness is open or shorted, Telematic Control Module circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 680

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0198 Mercury Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Telematic Control Module has not been received.

OBDII Code U0198 Mercury - Lost Communication With Telematic Control Module - AutoCodes.com — U0198 Mercury Code - Lost Communication With Telematic Control Module

What does this mean?

What are the Possible Causes of the DTC U0198 Mercury?

Faulty Telematic Control Module
Telematic Control Module harness is open or shorted
Telematic Control Module circuit poor electrical connection

How to Fix the DTC U0198 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0198 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U0198 Mercury Code

1. What does the OBDII code U0198 mean on a Mercury?

U0198 indicates a loss of communication with the Telematic Control Module (TCM), which manages vehicle telematics and communication features.

2. What are the common symptoms of code U0198?

Symptoms may include malfunctioning telematics features (e.g., navigation, remote functions), a lit Check Engine Light, or warning messages related to communication errors.

3. What causes the U0198 code to appear?

Causes include a faulty Telematic Control Module, damaged wiring or connectors in the CAN bus network, or issues with the power supply or ground connections to the TCM.

4. Can a low battery cause the U0198 code?

Yes, a low or weak battery can disrupt communication within the CAN bus system and trigger this code.

5. How do I diagnose the U0198 code on a Mercury?

Inspect the wiring and connectors to the TCM, check the power and ground connections, and use a scan tool to verify communication on the CAN bus network.

6. Is the U0198 code serious?

While it may not immediately affect driveability, the U0198 code can disable telematics functions, which may be important for safety or convenience features.

7. How can I fix the U0198 code?

Repairs may include replacing a damaged Telematic Control Module, repairing or replacing faulty wiring, or updating the module's software if required.

8. Can I clear the U0198 code without repairs?

Clearing the code without addressing the root cause is not recommended, as the issue will likely persist or reoccur.

9. How much does it cost to fix the U0198 code?

Repair costs vary, but replacing a Telematic Control Module can range from $300 to $800, excluding labor. Wiring repairs are generally less expensive.

10. Can the U0198 code be caused by a software issue?

Yes, outdated or corrupted software in the Telematic Control Module can cause communication failures and trigger the U0198 code.