U0100 on Ford: How to Diagnose & Fix
Lost Communication with ECM/PCM
4 Ford models · 4 documented issues · 3 critical · $1,200-$3,500 repair
U0100 on Ford by model: symptoms, diagnosis and fix
NHTSA recall 15V340 covers 2011-2012 Ford Fusion without the 3.5L engine (plus Lincoln MKZ Hybrid and 2011 Mercury Milan). A steering motor sensor fault can cause the electric power steering assist to shut down while driving. Owners notice heavier steering effort especially at low speeds, increasing crash risk. Dealers check the Power Steering Control Module (PSCM) for DTCs; if any loss-of-assist codes are stored, the steering gear is replaced free. 2010 Fusions had the same parts but were not included in the recall; NHTSA closed its investigation without adding 2010 models. 2010 owners can see the same symptoms, but those cars are not covered by the recall.
Common Symptoms
- Power steering warning message on dashboard
- Steering becomes heavy or requires extra force
- Intermittent loss of power steering assist
- Steering wheel off-center after loss of assist
- Clunking or grinding from steering column area
- Complete loss of power steering (requires significant force to turn)
- Steering assist comes and goes unpredictably
- Check engine light or power steering fault code stored
How to Fix
Check if your vehicle is covered under Ford recall (2011-2012 Fusion/MKZ power steering failure recall - free repair). For non-recall vehicles, the electric power steering rack must be replaced as a complete unit since the motor and control electronics are integrated. RepairPal estimates $1,958-3,362 installed. Remanufactured racks from PWR Steer or Cardone are available at $800-1,500, significantly cheaper than new OEM ($2,000+). Have the alignment performed after rack replacement.
Sources for this issue (1)
On 2025.5 F-150s with the 2.7L EcoBoost V6, the heater-core coolant hose routing was relocated. The new routing lets the coolant hose contact the engine wire harness at the C-clip attachment, abrading the harness insulation over time. This can chafe the harness or disconnect powertrain control module (PCM) connector pins, causing the engine to stall and increasing crash risk. Ford issued recall 25S63 for affected 2.7L EcoBoost trucks.
Common Symptoms
- Engine stalls unexpectedly while driving
- Stall-related warning lights
How to Fix
Dealers inspect and, as necessary, replace the engine wire harness, relocate the coolant hose, and add a Nyloguard protective covering over the harness — all free of charge under Ford recall 25S63. Owners experiencing an unexpected stall or stall-related warning lights should have the truck inspected promptly and verify recall eligibility by VIN at nhtsa.gov/recalls.
Sources for this issue (3)
The Mustang Mach-E 12V auxiliary battery drains prematurely, leaving the vehicle completely inoperable. Unlike ICE vehicles, the Mach-E cannot be jump-started in the traditional sense when the 12V dies — the vehicle cannot even unlock its doors or engage the HV system. The 12V battery charges from the main HV battery via a DC-DC converter, but software bugs can prevent proper charging when the vehicle is parked. OTA updates have addressed some scenarios, but the issue recurs for many owners.
Common Symptoms
- Vehicle completely unresponsive to key fob
- Cannot unlock doors or open frunk
- Phone-as-key does not work
- Dashboard shows no power at all
- FordPass app shows vehicle offline
- 12V battery voltage below 10V
How to Fix
Install the latest OTA software update, which includes improved 12V battery management. If the 12V battery has died, apply 12V power to the leads hidden below the right headlamp to open the frunk, then connect a 12V charger or jump pack to the terminals under the hood (positive terminal under a cap near the frunk). A battery tender connected when parked for extended periods prevents drain. If the issue recurs frequently, have the dealer test the DC-DC converter and replace the 12V battery ($150-250).
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (2)
On certain 2025 Explorers built December 6, 2023 through September 6, 2024 with the 2.3L EcoBoost, the powertrain control module (PCM) can unexpectedly reset while the vehicle is operating. The reset can damage the transmission's park system or cause the engine to stall. A damaged park system can let the vehicle roll away when shifted to Park without the parking brake applied, and an engine stall produces a sudden loss of drive power. Approximately 24,655 vehicles are covered. Ford traced the resets to an error in the PCM software and reported no crashes or injuries when it filed the recall.
Common Symptoms
- Vehicle rolls away after being shifted to Park
- Sudden loss of drive power / engine stall while driving
- Warning lights or messages on the dashboard
- Transmission not holding in Park
How to Fix
Visit a Ford dealer for the free recall remedy under campaign 25S35 (NHTSA 25V239000): dealers reprogram/update the powertrain control module software and inspect the transmission park system, replacing it if damaged. Until repaired, always set the parking brake when parking. Owner notification letters were mailed June 6, 2025. Ford customer service: 1-866-436-7332.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (3)
U0100 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does U0100 mean on a Ford?
U0100 stands for "Lost Communication with ECM/PCM." U0100 is a network communication code meaning a module has lost communication with the engine control module / powertrain control module (ECM/PCM) over the vehicle's data bus. The ECM/PCM is the brain that runs the engine, so when other modules can no longer 'talk' to it, the effects can be serious — a no-start, stalling, multiple warning lights, and many other modules logging faults at once. This is almost always a wiring, connector, power/ground, or bus fault, or a failure of the ECM/PCM itself, rather than a single sensor. It should be diagnosed promptly because the vehicle may be undrivable. On Ford it is documented across 4 models: Fusion, F-150, Mustang Mach-E, Explorer.
What are the most common causes of U0100?
The most common causes of U0100 are: Loss of power or ground to the ECM/PCM, CAN bus wiring damage, short, or open circuit, Corroded, loose, or damaged connectors at the module, Blown fuse feeding the ECM/PCM, Failed ECM/PCM, Another faulty module pulling down the data bus, Water intrusion or corrosion in a connector/harness. The specific cause varies by vehicle.
How much does it cost to fix U0100 on a Ford?
Published repair estimates on Ford range from $1,200 to $3,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for U0100 on a different make?
View U0100 across all makes →Join 700+ subscribers following Au7o for vehicle insights and updates.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.