U0198 on 2015-2019 Lincoln MKC: Lost Communication With Telematics Control Module Fixes

What's Unique About the 2015-2019 Lincoln MKC

For this generation of the Lincoln MKC, the TCU is integral to the "connected car" experience but is prone to two main issues: software glitches and 3G obsolescence. Lincoln has issued Technical Service Bulletins (TSBs) acknowledging that these modules can suffer from software glitches causing code U0198. Unlike many communication codes that point to complex wiring failures, the issue on the MKC is frequently resolved with a simple power cycle (fuse pull) or a software update. Additionally, a faulty TCU on this platform is a known cause of significant parasitic battery drain, killing the battery overnight.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Lincoln Way™ app fails to connect or update vehicle status.
• Remote commands from the app (start, lock, unlock) do not work.
• The modem's Electronic Serial Number (ESN) is blank or missing in the SYNC settings menu.
• An "SOS System Fault" message may appear on the instrument cluster.
• The in-vehicle Wi-Fi hotspot is inoperative.
• Significant parasitic battery drain, leading to a dead battery overnight or after a few days of not driving.

Most Likely Causes

1. TCU Software Glitch 🔴 High Probability As documented in Lincoln TSBs SSM 48267 and SSM 47160, these modules are known to enter a fault state that can be cleared by a hard reset. This is the most common and easiest fix to attempt first.
   How to confirm: The simplest way to confirm is to perform the fix. If pulling the fuse restores functionality, a software glitch was the cause.
   Typical fix: Perform a hard reset by removing the TCU fuse for at least 5 minutes, then reinstalling it. This is likely fuse F1 (10A) in the passenger compartment fuse box located below the glove box.
   Est. part cost: $0
2. Outdated TCU Software 🟡 Medium Probability TSB SSM 47160 specifically advises technicians to perform any open Field Service Actions (FSAs) to correct this condition, indicating that software updates were released to fix this bug.
   How to confirm: A Ford/Lincoln dealer or a shop with access to the Ford OASIS system can check the vehicle's VIN for open FSAs or available software updates for the TCU.
   Typical fix: Reprogram the TCU with the latest software using a dealer's Integrated Diagnostic System (IDS) tool.
   Est. part cost: $0
3. Obsolete 3G TCU Module 🟡 Medium Probability Models from 2015-2018 were equipped with 3G modems. As of 2022, cellular carriers have shut down their 3G networks, rendering these modules obsolete and unable to communicate. Ford's Customer Satisfaction Program 21B09 addressed this but has expired.
   How to confirm: If the vehicle is a 2015-2018 model and has never had its TCU replaced, it likely has a 3G unit. Physically inspect the module; 3G units have no external antenna ports, while 4G units have one or two round FAKRA ports. Part numbers starting with 'G' are 3G; 'H', 'J', 'K', or 'L' are 4G.
   Typical fix: The TCU must be replaced with a newer 4G-compatible module and a new 4G antenna. This new module will require programming to the vehicle using IDS or FORScan.
   Est. part cost: $65-$200 (Used), $250-$450 (New)
4. Failed Telematics Control Unit (TCU) ⚪ Low Probability Internal component failure can cause the module to stop communicating or, more specifically to this platform, fail to enter a low-power 'sleep' state, causing a parasitic battery drain.
   How to confirm: If a fuse pull and software updates do not resolve the code, and the unit is a 4G module, the TCU itself has likely failed internally. A parasitic draw test that shows a significant drop in amperage after pulling the TCU fuse confirms a faulty module.
   Typical fix: Replace the TCU. A replacement module, new or used, must be programmed to the vehicle (a process called Programmable Module Installation or PMI).
   Est. part cost: $65-$200 (Used), $250-$450 (New)

Rare But Worth Checking

• Blown Fuse or Wiring Issue: While less common than module software issues for this specific code, a blown fuse for the TCU or a damaged wire/connector between the TCU and the APIM can cause a loss of communication. Always check the fuse first.
• Parasitic Battery Drain from Faulty TCU: In some cases, the primary symptom owners notice is a dead battery, not the loss of app features. A diagnostic investigation of the battery drain often leads to the discovery of the U0198 code and a faulty TCU that refuses to go into sleep mode. Pulling the TCU fuse will stop the drain, confirming the TCU as the cause.

Diagnosis Steps

1. Verify the symptoms. Check if the Lincoln Way app connects, if the modem ESN is visible under Settings > General > About SYNC, and if you have experienced any unusual battery drain.
2. Scan for DTCs in all vehicle modules. Confirm that U0198 is present in the APIM.
3. Perform the TCU reset. Locate the passenger compartment fuse box below the glove box. With the vehicle off, pull fuse F1 (10A), wait 5 minutes, and reinstall it.
4. Clear all DTCs and re-test functionality. See if the app connects and if the code returns. Check for parasitic draw if battery issues are a concern.
5. If the issue persists, check for open recalls or Field Service Actions (FSAs) for your vehicle's VIN related to the TCU. This may require contacting a dealer.
6. If upgrading from 3G or replacing the TCU, locate the module in the rear cargo area under the floor cover, toward the rear seats. Visually inspect its connectors for corrosion or damage.
7. For DIY replacement, advanced users can use software like FORScan with an OBDLink EX adapter to perform the Programmable Module Installation (PMI) by writing As-Built data to the new module.
8. If all previous steps fail, the TCU is likely faulty or obsolete (if 3G) and requires replacement and programming by a dealer or qualified shop.

Parts You'll Likely Need

• Telematics Control Unit (TCU), 4G (OEM #KT1T-14G087-FK, HJ5T-14G087-UM, or other 'J' or 'K' series modules) — This is the module that fails, causes a battery drain, or becomes obsolete (3G shutdown), causing the U0198 code. A software glitch, internal failure, or outdated cellular technology within this unit is the root cause.
  Trusted brands: Motorcraft
  OEM price range: $250-$450
  Aftermarket price range: $65-$200 (Used/Remanufactured)
• 4G FAKRA Antenna (OEM #NL1Z-19A390-A) — When upgrading from an internal-antenna 3G module to a 4G module, a new external antenna is required to connect to the FAKRA port on the new TCU.
  Trusted brands: Ford, Bingfu
  OEM price range: $50
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• U3000 — This code means 'Control Module' and can be stored in the TCU itself, indicating an internal hardware or software failure.

Technical Service Bulletins (TSBs) & Recalls

• SSM 48267: Notes that U0198 can be caused by a TCU fault and recommends removing the TCU fuse for 5 minutes to correct the condition.
• SSM 47160: Links U0198 to inoperative remote app features and advises performing any open Field Service Actions (FSAs) and, if needed, a fuse pull before reprogramming the TCU.
• Customer Satisfaction Program 21B09: Provided a path for owners to upgrade their obsolete 3G TCUs to 4G units. The program documents confirm affected model years (2015-2017 MKC) and the service procedure.

Platform-Specific Known Issues

• TSB-Documented Software Faults: Lincoln Technical Service Bulletins SSM 48267 and SSM 47160 directly address DTC U0198 on these vehicles. They confirm that inoperative remote features are a known issue and that the primary repair steps are to perform a power cycle (fuse pull) and/or reprogram the TCU with updated software.
• 3G Network Shutdown: Models from 2015-2018 were often equipped with 3G TCUs. Due to the shutdown of 3G cellular networks in 2022, these modules are now obsolete and cannot connect for Lincoln Way app services, which will set a U0198 code. An upgrade to a 4G module is the only fix.
• Parasitic Battery Drain: A well-documented issue on 2015-2017 MKCs is a significant parasitic battery drain that kills the battery overnight. A common cause is a faulty TCU that fails to enter its low-power sleep mode. Diagnosticians have confirmed that pulling the TCU fuse resolves the drain, identifying the module as the culprit.

Mechanic-Grade Diagnostic Values

• Normal Parasitic Current Draw (Sleep Mode) — expected: Under 50-80 mA. Failure: A sustained draw of several hundred mA or even amps (e.g., 1.7A to 5A) after the vehicle should be asleep (approx. 40 minutes). Pulling the TCU fuse causes a significant, immediate drop in this current, confirming it as the source of the draw.
• CAN Bus Voltage — expected: CAN High (H) line should swing between 2.5V and 3.5V. CAN Low (L) line should swing between 2.5V and 1.5V.. Failure: A flat line, or voltage stuck high or low on either CAN line indicates a wiring short or a failed transceiver in a module on that bus.
• Ground Connection Resistance — expected: Less than 0.2 Ω. Failure: A reading higher than 0.2 Ω between the TCU's ground wire and a clean chassis point indicates a corroded or loose ground connection, which can cause communication issues.

Hidden / Shadow Codes Worth Checking

• U0198:00: The ':00' is a Fault Type Code (FTC) meaning 'No Sub Type Information'. It confirms the communication loss is total (module is offline) rather than a more specific data error. (see via Advanced scan tools like FORScan or the dealer's Ford IDS/FDRS system.)
• PID: TCU_AUTHSTATE: This is a live data Parameter ID, not a trouble code. It shows the authorization status of the TCU with Ford's servers. After a new installation, it may read 'Waiting for Authorization'. (see via FORScan or other advanced scan tools capable of reading live module data.)

Scan Tool Commands That Help

• FORScan: TCU Module Reset — This is the software equivalent of pulling the fuse. It's a quick first step to try and restore communication by commanding a hard reboot of the module.
• FORScan: TCU On-Demand Self-Test — Use this if a simple reset doesn't work. It actively polls the TCU and can sometimes re-establish a communication link that a simple reset does not.
• FORScan / Ford IDS: Programmable Module Installation (PMI) — This is required when a new or used TCU is installed. It involves writing the vehicle's specific 'As-Built' data to the new module to configure it correctly.
• FORScan: TCU As-Built editor (754-01-01: B100 0000 xx) — After installing a used TCU, this specific As-Built change is necessary to clear the VIN from the donor vehicle and prepare the module for authorization in the new vehicle.

Wiring & Ground Locations

• Telematics Control Unit (TCU) — In the rear cargo area, under the floor cover/spare tire access panel. It is mounted toward the front of that compartment, closer to the rear seats.. This is the physical location of the module that needs to be accessed for a fuse pull (if no fuse is dedicated), visual inspection, testing, or replacement.
• TCU Main Connector — The main electrical connector on the TCU module itself, located in the rear cargo area.. This connector provides power, ground, and CAN bus communication to the module. It should be inspected for corrosion, damage, or loose pins if communication is lost.

Real Owner Repair Stories

• CyanLabs Official Community user 'natet' (2017 Lincoln MKC) — Original 3G modem stopped working after the network shutdown, losing Lincoln Way app functionality.
  ❌ Tried (didn't work) Initially installed a 4G TCU with part number starting in 'L' (LB5T-14G087-SG). While FORScan could see the module, it would not integrate with the car because 'L' series TCUs are for newer vehicles with a different (HS4) CAN bus network.
  ✅ What actually fixed it Replaced the incompatible 'L' series TCU with a 'J' series TCU. This restored communication and allowed the 4G upgrade to function correctly.
• YouTube channel 'Pine Hollow Auto Diagnostics' (2017 Lincoln MKC with 36,000 miles) — Severe parasitic battery drain (nearly 5 amps) that would kill a brand new battery overnight.
  ❌ Tried (didn't work) The dealership replaced the battery without diagnosing the draw., Initial fuse pulls in the underhood fuse box did not isolate the circuit.
  ✅ What actually fixed it The draw was traced to the passenger compartment fuse box (BCM). Further diagnosis in a follow-up video confirmed the Telematics Control Unit (TCU) was the source of the draw. Pulling the TCU fuse resolved the massive drain.

OEM Part Supersession History

• Various 'G' series PNs (e.g., Gxxx-14G087-xx) → 'H', 'J', or 'K' series PNs (e.g., HJ5T-14G087-UM) — Upgrade from obsolete 3G cellular technology to 4G LTE technology following the 3G network shutdown in 2022.
  Heads up: TCUs starting with 'L' (e.g., LB5T-14G087-SG) are for newer vehicles with a different HS4 CAN bus and are NOT compatible with the 2015-2019 MKC, even though they are 4G. A 'J' or 'K' series module is the correct upgrade path.
• HJ5T-14G087-UE / -UF → HJ5T-14G087-UM (firmware) — The -UM calibration was released to fix bugs and restore full functionality (like Go Times and Value Charging for PHEV/BEV models) on earlier 'H' and 'J' series 4G TCUs.
  Heads up: Flashing a 'J' or 'K' series TCU with 'H' series firmware (or vice-versa) will fail, as the hardware is different. FORScan will typically abort the procedure, preventing the module from being bricked.

Model Year Variations Within This Range

• 2017 MKC (and some MKX models): While most MKC models have the TCU in the rear cargo area, some forum posts for 2017 models suggest the TCU may be located under the center console, accessible from the passenger side footwell. This location is less common for the MKC but worth checking if it's not found in the rear.