U0198 on 2012-2016 Ford Focus Electric: Lost Communication With Telematics Control Unit

What's Unique About the 2012-2016 Ford FOCUS ELECTRIC

The Ford Focus Electric from this era was heavily reliant on its TCU and the MyFord Mobile app for key EV features like remote start, checking charge status, finding the vehicle, and pre-conditioning the cabin. These early TCUs used the 3G cellular network. With the widespread shutdown of 3G networks by carriers like AT&T in February 2022, most of these original units became obsolete, leading to systemic communication failures and the U0198 code. This isn't just a random part failure; it's a case of planned obsolescence tied to the evolution of cellular technology. Ford offered a customer-paid upgrade program (FSA 21B09) to a 4G unit, but many owners now opt to simply disable the old TCU to prevent battery drain.

Diagnostic Flowchart

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

Symptoms You May Notice

• MyFord Mobile app features are inoperative (remote start, lock/unlock, charge status, vehicle location).
• A 'No Modem ESN' message may appear in the vehicle's system settings under the SYNC menu.
• Intermittent or persistent draining of the 12-volt battery, as the TCU continuously searches for a non-existent 3G network and fails to enter a low-power sleep mode. This can lead to a dead 12V battery even if the car is plugged in.
• A telematics warning light or message may appear on the infotainment screen.
• The radio may display a message about shutting down to save power as the 12V battery depletes.

Most Likely Causes

1. Obsolete 3G Telematics Control Unit (TCU) 🔴 High Probability The original TCUs in these vehicles were 3G-only. All major US carriers shut down their 3G networks by 2022, making communication impossible for these modems.
   How to confirm: If the MyFord Mobile app stopped working around 2022 and the U0198 code appeared, the 3G shutdown is the cause. Pulling fuse F1 in the trunk and seeing the 12V battery drain disappear confirms the TCU is the source of the drain.
   Typical fix: 1) Upgrade the 3G TCU to a 4G unit. Ford offered a customer-paid program (FSA 21B09) where the owner bought the kit and Ford covered labor. This program had expiration dates but was extended multiple times. 2) The common workaround is to permanently remove the TCU fuse (F1, a 5A fuse in the trunk fuse panel) 🎬 See this guide to locating all Ford Focus fuse boxes to prevent battery drain, forgoing app functionality.
   Est. part cost: $200-$500 for a 4G upgrade kit. $0 for the fuse pull workaround.
2. TCU Software/Firmware Glitch 🟡 Medium Probability Before the 3G shutdown, communication modules could experience software faults that caused them to lock up or stop responding, causing the same symptoms.
   How to confirm: A temporary fix by pulling the TCU fuse (Fuse F1, a 5A fuse in the trunk fuse panel) for 5 minutes and reinstalling it often restores communication temporarily. If this works but the problem returns, it's a software issue.
   Typical fix: A Ford dealer can reprogram the TCU with the latest software using their IDS scan tool, as directed by TSBs like SSM 47428. However, this will not fix a unit rendered obsolete by the 3G shutdown.
   Est. part cost: $0 for a fuse pull reset; dealer programming may cost 1-2 hours of labor.
3. Failed Telematics Control Unit (TCU) 🟡 Medium Probability Beyond the 3G issue, the electronic module itself can fail internally. This can cause a hard communication fault and often a significant parasitic drain on the 12V battery as the module fails to sleep.
   How to confirm: If a software update and fuse pull do not resolve the issue (and the fuse is reinstalled), and the 12V battery repeatedly drains, the TCU hardware is likely faulty. A parasitic draw test will point to the TCU circuit.
   Typical fix: Replace the TCU. This is almost always done as part of the 4G upgrade, as sourcing a new 3G unit is pointless.
   Est. part cost: $300-$600 for a replacement TCU.
4. Weak or Failing 12V Battery ⚪ Low Probability Like all modern cars, low voltage from a weak 12V battery can cause random communication faults between modules. The TCU issue is a known battery killer, so a weak battery is often a symptom rather than the root cause.
   How to confirm: Test the 12V battery's health, state of charge, and ability to hold a charge. A battery resting below 12.4V is suspect. If a new battery is installed and it also drains, the cause is not the battery itself.
   Typical fix: Replace the 12V AGM battery. This is often necessary *after* the TCU has damaged the old one, but it won't fix the underlying U0198 code or parasitic drain.
   Est. part cost: $150-$250

Diagnosis Steps

1. Verify symptoms: Confirm that MyFord Mobile app features are not working and that U0198 is the primary code stored in the APIM.
2. Perform the TCU Reset/Bypass: Locate the fuse panel in the trunk. 🎬 Watch: How to find the fuse box locations Pull fuse F1 (a 5A fuse) for at least 5 minutes. This serves two purposes: 1) As a reset, you can reinstall it to see if communication returns temporarily. 2) As a bypass, you can leave it out to see if your 12V battery drain issue is resolved. If the drain stops, the TCU is the culprit.
3. Check for TSBs and FSAs: While the programs are likely expired, a Ford dealer can still check your VIN for history related to FSA 21B09 (the 4G upgrade program) and TSBs like SSM 47428 and SSM 47161. This confirms the vehicle's history with this specific issue.
4. Check 12V Battery Health: After leaving the F1 fuse out overnight, test the 12V battery to ensure it is holding a charge above 12.4V. If it was previously draining and now holds a charge, this confirms the TCU was the source of a parasitic draw.
5. Advanced Scan: Use a Ford-capable scanner (like FORScan) to confirm U0198 is present in the APIM. Check if a modem ESN is visible in the module data; if it is blank or shows an error, it confirms the communication loss.
6. Decide on a path: 1) Live without the app: Leave fuse F1 pulled permanently. This is the most common, no-cost solution. 2) DIY 4G Upgrade: Source a compatible 4G TCU from another Ford vehicle (e.g., an Escape) and use FORScan to program it. This is a complex but documented process in owner forums. 3) Shop-Installed 4G Upgrade: Find a dealer or independent shop willing to install the official 4G upgrade kit, which you will have to pay for out of pocket.

Parts You'll Likely Need

• Telematics Control Unit (4G Upgrade Kit) (OEM #AMMU7J A00A25 BA) — This is the official Ford kit for the Focus Electric to fix the obsolete 3G TCU. It restores app functionality with a modern 4G modem. Availability may be limited.
  Trusted brands: Motorcraft
  OEM price range: $300-$500
• Used 4G Telematics Control Unit (DIY) (OEM #e.g., HJ5T-14G087-UF (from a 2017-19 Escape)) — For DIY repair, owners source used 4G TCUs from other Ford models like the Escape. This requires custom programming with FORScan and may require a separate cellular antenna.
  Trusted brands: Used OEM (from eBay or salvage yards)
  OEM price range: $50-$150
• 5 Amp Mini Fuse — Not for replacement, but for pulling from the F1 slot in the trunk fuse panel to disable the TCU. It's the 'part' needed for the zero-cost fix.
  Trusted brands: Generic
  OEM price range: <$1

Technical Service Bulletins (TSBs) & Recalls

• FSA 21B09: Ford's official 'Customer Satisfaction Program' to address the 3G network shutdown. It detailed the process for a customer-paid upgrade to a 4G TCU, where Ford would cover the labor. It confirms the issue affects Focu

Platform-Specific Known Issues

• The primary issue is the planned obsolescence of the 3G TCU. The shutdown of 3G cellular networks by carriers has rendered the original telematics system non-functional, making U0198 a very common code on these vehicles as they age.
• A faulty or obsolete TCU is a notorious cause of parasitic drain on the 12V battery, leading to a no-start condition even if the high-voltage battery is fully charged. This is the most frustrating symptom for owners.
• Loss of the MyFord Mobile app is more significant for the Focus Electric than for an ICE vehicle, as it removes the ability to remotely check state of charge and precondition the cabin, which are important EV ownership features.

Mechanic-Grade Diagnostic Values

• MS-CAN Bus Voltage — expected: Approximately 2.3V for CAN- and 2.7V for CAN+, with both summing to ~5V. Voltages should mirror each other during communication.. Failure: CAN- shorted to ground (0V), CAN+ shorted to power (~5V or ~12V), or both lines showing identical static voltage indicates a bus fault.

Hidden / Shadow Codes Worth Checking

• U0198:00-0B: A sub-code indicating 'Lost Communication With Telematic Control Module 'A''. The '-0B' status indicates the DTC was present at the time of the request and the malfunction lamp is off. This provides more detail than the generic U0198 code. (see via Advanced diagnostic tools like FORScan or the dealer's IDS can read these extended DTCs from the APIM.)

Scan Tool Commands That Help

• FORScan: APIM Module Reset — This function can be used to force the APIM (Sync module) to re-establish communication with all modules on the network. It can sometimes temporarily clear the U0198 code if the issue is a software glitch, but it will not fix an obsolete 3G modem.
• FORScan: TCU Authorization / Programming — When performing a DIY upgrade from a 3G to a 4G TCU, FORScan is required to program the new module. This involves writing As-Built data from the old TCU (if possible) or from a similar vehicle, and running an authorization sequence to link the new modem to the FordPass app.
• Ford IDS: TCU Reprogramming — As per Customer Satisfaction Program 17B07, dealers use IDS to reprogram the TCU to fix a software condition that could drain the 12V battery. This was a common fix before the 3G network shutdown rendered the hardware obsolete.

Wiring & Ground Locations

• Telematics Control Unit (TCU) — Located in the trunk, behind the left-side trim panel, typically mounted to the inner fender structure.. This is the physical module that needs to be accessed for replacement, upgrade, or to disconnect its wiring harness as an alternative to pulling the fuse.
• TCU Ground — The TCU is grounded through its mounting bolts to the chassis. The main chassis ground points for the rear of the vehicle are located behind the trunk trim panels. For the front, key grounds are under the airbox.. A poor ground connection can cause intermittent communication issues and is a potential, though less common, cause for the U0198 code compared to the 3G shutdown. Cleaning the main battery-to-chassis grounds is a known fix for various electrical issues on the Focus platform.
• Fuse F1 (Rear Junction Box) — In the fuse panel located in the trunk, on the left side behind a small access door.. This 5A fuse provides power to the TCU. Pulling this fuse is the most common and effective way to disable the obsolete 3G TCU and prevent it from causing a parasitic drain on the 12V battery.

Real Owner Repair Stories

• Ford Focus Electric Forum user 'lfhoward' (2016 Ford Focus Electric) — 12V battery was going dead due to the old, defunct 3G TCU constantly searching for a network.
  ❌ Tried (didn't work) Leaving the original 3G TCU connected.
  ✅ What actually fixed it The owner performed a DIY upgrade to a 4G TCU sourced from a 2017 Ford Escape. They used FORScan software to flash the most recent firmware to the new module. This resolved the battery drain problem and restored telematics functionality via the FordPass app.

OEM Part Supersession History

• TCUs with suffix 'A' or 'B' → DM5Z-19A387-C and later revisions — According to TSB 15-0134, early TCUs with suffix A or B were prone to causing a 12V battery drain and were to be replaced with an updated part.
  Heads up: This TSB was issued before the 3G shutdown. While part number DM5Z-19A387-C was an update, it was still a 3G modem and is now also obsolete. The current upgrade path is to a 4G modem kit.

Model Year Variations Within This Range

• 2012-2013: Vehicles built on or before 9/2/2013 were specifically called out in TSB 15-0134 for inspection of the TCU part number suffix due to battery drain issues. Additionally, a recall (13S09) was issued for 2012-2014 models for a PCM software issue that could cause a stall, which required a dealer reprogram.
• 2016: A specific Customer Satisfaction Program (17B07) was issued for 2016 Focus Electric models to reprogram the TCU for a battery drain condition that could occur after several days of inactivity. This was a software fix performed by dealers using IDS.