U0140: How to Diagnose & Fix — Lost Communication with BCM
25 vehicles · 17 makes · $10-$2,500 repair
How to diagnose and fix U0140: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Jaguar S-TYPE · 2000–2008
The S-TYPE is notorious for electrical gremlins caused by moisture ingress into control modules and poor CAN bus connections. Phantom warning lights, inoperative features, and intermittent faults across multiple systems are common and difficult to diagnose without dealer-level equipment.
Common Symptoms
- Multiple warning lights illuminated simultaneously
- Windows or locks operating erratically
- Instrument cluster errors or flickering
- Intermittent no-start condition
- Features working one day and not the next
How to Fix
Check all module locations for moisture ingress, particularly the driver footwell and trunk. Clean and reseal all CAN bus connectors with dielectric grease. Reprogram affected modules with the latest software. Replace the 12V battery if it is over 4 years old.
Owner tips & cautions
- TipBuy an iCarsoft i930 Jaguar-specific scanner. It reads all Jaguar modules and saves thousands in dealer diagnostic fees. Essential tool for S-TYPE ownership.
Jaguar XJ · 2004–2012
The XJ suffers from cascading electrical faults caused by body control module (BCM) software glitches and CAN bus communication errors. Phantom warning lights, inoperative features, and intermittent failures across multiple systems are common, especially after battery disconnection or jump-starting.
Common Symptoms
- Multiple random warning lights illuminated
- Windows or sunroof operating on their own
- Central locking malfunction
- Instrument cluster errors
- Intermittent failure of various electrical accessories
How to Fix
Have the BCM reprogrammed with the latest JLR software at a dealer. Check all ground connections for corrosion, especially the main chassis ground behind the engine. Replace the 12V battery with a genuine Jaguar-spec AGM battery. Avoid jump-starting without a proper battery management system.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Owner tips & cautions
- TipAlways maintain the 12V battery in good condition. A weak battery is the #1 cause of BCM glitches on the XJ. Use a battery tender if the car sits for more than a week.
Dodge Magnum · 2005–2008
The Dodge Magnum suffers from widespread electrical problems centered around the TIPM (Totally Integrated Power Module) and the steering column control module (clockspring). Symptoms include dash lights flickering or going completely dark while driving, headlights cutting out at night, loss of turn signals, wipers, horn, and cruise control all at once. The steering column module failure is particularly dangerous as it can disable multiple safety systems simultaneously. The TIPM relay failures can cause no-start conditions, fuel pump cutouts, and random electrical gremlins throughout the vehicle.
Common Symptoms
- Dashboard lights flickering or going completely dark while driving
- Headlights cutting out intermittently, especially at night
- Loss of turn signals, wipers, horn, and cruise control simultaneously
- Vehicle cranks but will not start intermittently
- Fuel pump stops running randomly while driving
- Warning lights illuminating on dash without clear cause
How to Fix
For steering column module failure (loss of wipers, horn, turn signals, cruise control simultaneously), replace the clockspring assembly ($150-$300 part, $200-$400 labor). For TIPM-related issues, have the relays tested — individual relay replacement is sometimes possible ($50-$150), but full TIPM replacement runs $400-$800 for the module plus programming. For flickering dash lights, check the instrument cluster ground connections and the body harness ground behind the left kick panel.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Mopar 56049795AE clockspring / steering-column control module
Replace when steering-wheel functions and clockspring/module testing isolate this assembly Fitment: Product fitment includes Magnum configurations; verify VIN/options and airbag procedure Live OEM direct-product page when checked
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Sources for this issue (1)
Ford Transit · 2015–2020
Jeep Grand Wagoneer · 2021–2024
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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?
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.
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?
Repair costs for U0140 range from $10 to $2,500, depending on the vehicle and root cause.
Which vehicles are affected by U0140?
Au7o has documented U0140 across 25 vehicle models from 17 manufacturers: Alfa Romeo, Audi, Cadillac, Chevrolet, Dodge, Ford, GMC, Honda, Hyundai, Jaguar, Jeep, Kia, Land Rover, MINI, Mercedes-Benz, Pontiac, Toyota.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.