U0146 on 2023-2026 Ford F-450 SD: Causes of Lost Communication Codes

What's Unique About the 2023-2026 Ford F-450 SD

The 2023-2025 Ford Super Duty platform is unique regarding code U0146 because Ford has issued multiple Technical Service Bulletins (TSBs) acknowledging a specific software-related issue. The code is known to be set in the ABS module after the vehicle is remote started because another module, the Image Processing Module A (IPMA), is slow to communicate on the network. [SSM 51486] Ford explicitly advises in TSBs like SSM 53521 that if no symptoms are present, the code should be ignored and that replacing modules will not resolve this specific condition.

Diagnostic Flowchart

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

Symptoms You May Notice

• "Parking Brake Limited Function" message on the dashboard. [SSM 54420, SSM 54160]
• "Park Assist Unavailable" message on the dashboard. [SSM 54420, SSM 54160]
• "Check Brake System" message on the dash.
• ABS warning light illuminated
• Check engine light illuminated.
• BRAKE light remains illuminated on the dash.
• Inoperative FordPass App features (remote start, lock/unlock).

Most Likely Causes

1. Software Anomaly After Remote Start 🔴 High Probability Multiple Ford TSBs (SSM 51486, SSM 53521) directly identify a timing issue on the CAN network during remote start events on 2023-2025 models, causing the ABS module to log this code. The IPMA is slow to wake up, triggering the fault. [SSM 51486]
   How to confirm: Note if the code and any warning messages only appear immediately following a remote start and clear on the next key cycle. If there are no other persistent symptoms, Ford advises ignoring the code as it does not affect vehicle operation.
   Typical fix: No service action is required if no symptoms are present. If symptoms persist or other codes are active, a dealer can perform a software update on the affected modules (ABS, GWM, IPMA) using the Ford Diagnostic & Repair System (FDRS). Module replacement is explicitly not recommended.
   Est. part cost: $0
2. Low Battery Voltage 🟡 Medium Probability → Shop Vehicle Battery Modern trucks with many electronic modules are sensitive to voltage. A weak battery can cause random communication codes during the high-demand startup sequence. TSB 23-2199 for the F-150 also points to low battery state of charge (SoC below 80%) as a cause for similar communication issues requiring a GWM update.
   How to confirm: Test the battery's state of charge and health using a digital battery tester. Voltage should be above 12.4V at rest. Use a scan tool like FORScan or FDRS to check the Battery State of Charge (BATT_SOC) PID, which should be 80% or higher.
   Typical fix: Recharge or replace the battery. Ensure the battery monitoring system (BMS) is reset after replacement to ensure proper charging and system function.
   Est. part cost: $250-$450
3. CAN Bus Wiring or Connector Issue ⚪ Low Probability While less common on new vehicles, wiring harnesses can still be damaged, and connectors can be loose or corroded, interrupting network signals. Connectors under the truck are exposed to the elements and road debris.
   How to confirm: A technician must perform a visual inspection of the wiring harnesses between the ABS module, Gateway Module (GWM, often part of the Body Control Module or located behind the passenger kick panel), and IPMA (located behind the dashboard/glovebox). This is followed by network diagnostic tests with a multimeter or oscilloscope to check for continuity and resistance.
   Typical fix: Repairing the damaged section of the wiring harness or cleaning/securing the affected connector. Applying dielectric grease can help prevent future corrosion.
   Est. part cost: $5-$50
4. User-Made FORScan Programming Changes ⚪ Low Probability The vehicle's network is sensitive to configuration changes. Users making modifications with tools like FORScan (e.g., changing tire size) have reported inadvertently triggering a persistent U0146 code that won't clear.
   How to confirm: The code appears immediately after writing a change to a module with FORScan. Reverting to the original 'as-built' data for the modified module may or may not clear the code.
   Typical fix: First, try reverting to the original module configuration. If that fails, a dealer visit may be necessary to have the module professionally reprogrammed with FDRS to restore proper communication pathways.
   Est. part cost: $0 - $250

Rare But Worth Checking

• Faulty Control Module (ABS, GWM, or IPMA): This is rare and should only be considered after all software, battery, and wiring issues have been completely ruled out. The TSBs specifically warn against replacing modules for the remote start issue. A module failure would likely present with more persistent and severe symptoms than just a transient code.

Diagnosis Steps

1. Check for accompanying symptoms like warning lights or functional problems. If none exist and the code appeared after a remote start, clear the code and monitor. Per Ford TSBs, no further action may be needed.
2. If symptoms are present, use a high-level scan tool like Ford's FDRS to check for software updates for the ABS, GWM, and IPMA modules. This is the most common official fix.
3. Thoroughly test the vehicle's 12V battery. Ensure it is fully charged (above 12.4V) and healthy, and that the BATT_SOC PID is above 80%. Low voltage is a common cause of communication faults.
4. If any changes were recently made using FORScan, revert the module data to the original 'as-built' configuration and attempt to clear the code.
5. Visually inspect the wiring and connectors for the ABS module, GWM (often behind the passenger kick panel), and IPMA (behind the dashboard/infotainment screen). Look for any signs of damage, corrosion, or loose pins.
6. If wiring appears intact, a technician can perform CAN bus network diagnostics to check for signal integrity, proper resistance (60 Ohms across the network), and voltage.
7. Only consider replacing a control module as a final step after all other software, battery, and wiring possibilities have been exhausted.

Parts You'll Likely Need

• Vehicle Battery (OEM #BAGM-48H6-760 (Motorcraft example, verify for specific vehicle)) — A weak battery can cause intermittent communication faults during startup. This is a common and relatively simple fix to rule out before proceeding to more complex diagnostics.
  Trusted brands: Motorcraft
  OEM price range: $300-$450
  Aftermarket price range: $250-$400

Related Codes That Often Appear With This One

• U0151 — Lost Communication With Restraints Control Module. Often set alongside other communication codes during a network disruption. [SSM 54420]
• U023A — Lost Communication With Image Processing Module 'A'. This is a key code, as Ford TSBs identify the IPMA's slow startup as the root cause for U0146 during remote start. [SSM 51486, SSM 53521]
• U0159 — Lost Communication With Parking Assist Control Module. This directly relates to the 'Park Assist Unavailable' message. [SSM 54420, SSM 54160]
• U0415 — Invalid Data Received From Anti-Lock Brake System Control Module. This indicates other modules are receiving corrupted data from the ABS module, which is struggling with its own communication issues. [SSM 54420, SSM 54160]
• U2402 — Lost Communication with BCM. Seen in conjunction with U0146 on F-150s with similar GWM software issues, indicating a broader communication problem.

Technical Service Bulletins (TSBs) & Recalls

• SSM 54420: Mentions U0146 in conjunction with brake system warning messages like 'Parking Brake Limited Function'.
• SSM 54160: Also links U0146 to 'Parking Brake Limited Function' messages.

Platform-Specific Known Issues

• TSB SSM 53521 and SSM 51486 state that on 2023-2025 F-Super Duty vehicles, DTCs U0146, U023A, and U0159 may be set in the ABS module after a remote start. This is due to the IPMA not communicating quickly enough. Ford states that module replacement will not resolve this and the codes should be ignored if no other symptoms are present.
• Customer Satisfaction Program 23B21 for the F-150 Lightning highlights a similar issue where the GWM loses internet connection, causing FordPass app issues and setting U0146. The fix is a GWM software update.
• Users on forums like ford-trucks.com have confirmed that making changes with FORScan can trigger a persistent U0146, reinforcing the network's sensitivity to software configuration.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: 60 Ohms (± a few ohms) between CAN_H and CAN_L pins at the DLC or any module connector (with battery disconnected).. Failure: A reading of 120 Ohms indicates a missing termination resistor or an open in the circuit. A reading near 0 Ohms indicates a short between the CAN wires. A reading around 40-45 Ohms could indicate a third, unintended termination resistor on the bus.
• CAN Bus Voltage (Key On, Engine Off) — expected: CAN_H to ground should be ~2.5V to 3.0V. CAN_L to ground should be ~2.5V to 2.0V.. Failure: Voltages that are stuck high, low, or at 0V on either line indicate a short to power or ground. Both lines reading the same voltage (e.g., 2.6V) can indicate an idle bus or a fault condition.
• Module Ground Resistance — expected: ≤ 0.1 Ω between the module's ground pin and a clean chassis ground point.. Failure: High resistance (anything over a few tenths of an ohm) indicates a poor ground connection, which can cause intermittent communication faults.

Hidden / Shadow Codes Worth Checking

• U0146:00: The ':00' is a Fault Type Byte (FTB) meaning 'No Sub Type Information'. This indicates that the base DTC text ('Lost Communication With Gateway A') provides the complete description of the fault, without needing further detail. It is commonly seen on Ford vehicles for general communication failures. (see via This is visible on professional scan tools like Ford's FDRS and advanced tools like FORScan.)

Scan Tool Commands That Help

• Ford FDRS: Network Test — This is the initial test run when connecting FDRS to the vehicle. It pings all expected modules on the network and color-codes them: green for communicating, gray for not responding, and orange for communicating with DTCs stored. This quickly identifies which modules are offline.
• Ford FDRS: GWM - Software Update — Used when a TSB or diagnostic flow indicates a software fix is available for the Gateway Module. This is a primary fix for many communication issues on modern Fords.
• Ford FDRS: Self-Test (CMDTCs) — To retrieve all Continuous Memory Diagnostic Trouble Codes from a specific module (like the ABS module) or all modules simultaneously.
• FORScan: Reset GWM module — This function in FORScan can force a reboot of the Gateway Module. This can sometimes temporarily restore communication if the module is in a locked-up state due to a software glitch.

Wiring & Ground Locations

• Gateway Module (GWM) — On modern Super Duty and F-150 trucks, the GWM is typically located behind the passenger side glove box or kick panel area.. This is the central router ('Gateway A') that the ABS module is failing to communicate with. All diagnostic paths for U0146 lead back to this module and its connections.
• ABS Control Module — Typically located in the engine bay on the driver's side frame rail, often integrated with the hydraulic pump assembly.. This is the module that is logging the U0146 code, as it is the one detecting the loss of communication from the GWM.
• Driver Side Chassis Ground — In the engine bay on the driver's side, there is a common chassis ground point often used for diagnostics and accessory installation.. A poor ground for either the ABS module or the GWM can cause a voltage differential that disrupts CAN bus communication. Verifying a clean, tight ground connection is a key step.
• Passenger Side Chassis Ground — Behind the battery box on the passenger side fender is another primary chassis ground point.. This ground is critical for modules located on the passenger side of the vehicle, including potentially the GWM. Access may require removing the battery and its tray.

Real Owner Repair Stories

• Ford Truck Enthusiasts Forum (2025 Ford F-450) — A persistent Check Engine Light with code U0146 appeared immediately after making a change.
  ❌ Tried (didn't work) Performing a PCM, TCM, and AWD module relearn., Clearing the codes multiple times.
  ✅ What actually fixed it The user had changed the tire size using FORScan. The final resolution was to revert the tire size value back to the original setting to clear the persistent U0146 code.

When the Usual Fixes Don't Work

• While the provided TSBs strongly suggest that U0146 on these trucks is a benign software glitch related to remote start, real-world owner reports provide a critical counterpoint. A user on the Ford Truck Enthusiasts forum triggered a persistent, non-clearing U0146 code immediately after changing the tire size parameter with FORScan. This demonstrates that incorrect software configuration, even by a user, can cause a 'hard' fault that is not temporary and requires reverting the change to fix. This proves the network's sensitivity and shows that not all instances of U0146 can be dismissed, especially if aftermarket programming tools have been used.

Model Year Variations Within This Range

• 2023-2025: Ford TSBs SSM 51486 and SSM 53521 specifically call out these model years for setting U0146 in the ABS module after a remote start. This indicates a known software timing issue in the initial production years of this generation that may be resolved in later software updates or model years.