Lost Communication with Telematics Control Module
The U0198 code indicates that the vehicle's main control module (ECM, PCM, or network master module) has lost communication with the Telematics Control Module (TCM). The TCM manages connectivity functions such as emergency services, roadside assistance, remote diagnostics, and data communications. This loss of communication is detected when the network master module does not receive valid messages from the TCM over the CAN data bus for a specified period, or when signal quality is insufficient for stable communication.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Faulty Telematics Control Module (TCM)
- Open or shorted CAN bus wiring, damaged connectors, or corroded terminals
- Failed CAN bus termination resistor
- Power supply issue to the TCM (blown fuse, poor ground connection)
- Electromagnetic interference on the communication line
- Corrupted or outdated TCM software
- Faulty network master module
3. Symptoms You Will Notice
- Malfunction indicator lamp (MIL) illuminated
- Loss of telematics features (e.g., emergency call, remote services, navigation data)
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Check for blown fuses and verify power and ground at the TCM connector
Inspect CAN bus wiring and connectors for damage, corrosion, or loose connections
Test CAN bus termination resistance (should be ~60 ohms with network powered off)
Attempt to communicate with the TCM using a scan tool; if no response, suspect TCM failure
Check for technical service bulletins (TSBs) related to TCM software updates
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but telematics features like emergency call and remote diagnostics will be unavailable. Have the issue diagnosed promptly to restore full functionality.
How much does it cost to fix?▼
Repair costs vary widely: from $100–$200 for a blown fuse or wiring repair, to $500–$1,500 for TCM replacement and programming.