U0140 on Ford: How to Diagnose & Fix
Lost Communication with BCM
3 Ford models · 3 documented issues · 2 critical · $250-$1,200 repair
U0140 on Ford by model: symptoms, diagnosis and fix
Ford Transit BCMs, particularly on 2015–2019 models, have been reported to fail or develop software faults causing a wide array of seemingly unrelated electrical issues including random door lock cycling, instrument cluster malfunctions, and accessory power loss. Water intrusion from sunroof drains or cowl leaks can accelerate BCM failure by corroding the module's internal connectors. Ford TSB 18-2175 acknowledged BCM programming faults contributing to some of these behaviors.
Common Symptoms
- Random door locks cycling or activating on their own
- Instrument cluster warning lights illuminating without cause
- Power windows or accessories becoming inoperative intermittently
- Battery drain or parasitic draw
- Multiple unrelated fault codes stored across modules
How to Fix
Diagnose with Ford IDS/FDRS scan tool to identify BCM fault codes. If water intrusion is present, address the leak source first. BCM replacement (Ford part number varies by configuration, ~$300–$500 OEM) and programming/configuration to the vehicle using Ford PATS and IDS is required. In some cases, a BCM software update alone resolves the issue.
Sources for this issue (1)
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, use the manual door release (under the front left fender), 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).
Sources for this issue (1)
The washer reservoir and pump seal leaks, and washer fluid runs down the pump's wiring. Capillary action carries the fluid inside the wire insulation the full length of the harness to the BCM connector in the passenger footwell, where it corrodes the pins and the module itself. The result is a car full of unrelated electrical faults - flickering lights, dead windows and locks, random warning messages, phantom battery drain overnight, and eventually a no-start. Replacing the BCM without fixing the leak and the wet harness simply kills the new module, which is why owners often go through two.
Common Symptoms
- Battery drains overnight
- Random warning messages on the dash
- Power windows or door locks stop working
- Interior and exterior lights flicker
- Intermittent no-start
- Washer fluid disappears or pools under the front of the car
How to Fix
Find and stop the leak first: replace the washer pump/grommet (and the reservoir if cracked) with the updated design. Then cut back and replace the wetted section of harness - the corroded wire must be removed, not just dried, because fluid travels inside the insulation. Clean or replace the BCM connector, and only then replace and program the BCM if it is confirmed dead. Check for the classic parasitic draw before condemning the battery or alternator.
Sources for this issue (3)
U0140 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 U0140 mean on a Ford?
U0140 stands for "Lost Communication with BCM." U0140 is a network communication code meaning a module has lost communication with the body control module (BCM) over the vehicle's data bus. The BCM oversees many body and convenience functions — lighting, door locks, windows, wipers, anti-theft, and gateway communications — so losing contact with it can cause a wide range of seemingly unrelated electrical problems and warning lights. This is typically a wiring, connector, power/ground, or bus fault, or a failure of the BCM itself. Because the BCM often acts as a communication hub, this code can appear alongside other 'lost communication' codes. On Ford it is documented across 3 models: Transit, Mustang Mach-E, Focus.
What are the most common causes of U0140?
The most common causes of U0140 are: Loss of power or ground to the BCM, CAN/data bus wiring damage, short, or open circuit, Corroded, loose, or damaged BCM connectors, Blown fuse feeding the BCM, Failed body control module, Water intrusion or corrosion in the harness, Another module faulting the shared data bus. The specific cause varies by vehicle.
How much does it cost to fix U0140 on a Ford?
Published repair estimates on Ford range from $250 to $1,200 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 U0140 on a different make?
View U0140 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.