U0140 on Alfa Romeo: How to Diagnose & Fix
Lost Communication with BCM
2 Alfa Romeo models · 2 documented issues · 2 critical · $300-$1,500 repair
U0140 on Alfa Romeo by model: symptoms, diagnosis and fix
Water enters the cowl/firewall area (failed bulkhead gasket, detached fresh-air vent, or clogged A/C evaporator drain) and drips onto the Body Control Module and wiring loom in the passenger footwell. The resulting corrosion and shorts cause wide-ranging, intermittent electrical failures. Owners have reported headlights, brake lights, turn signals, and driver-assist systems all cutting out at speed, plus dead batteries and warning-light storms.
Common Symptoms
- Multiple warning lights / dashboard errors
- Lights or signals failing while driving
- Wet passenger footwell carpet
- Repeated dead/drained battery
- Intermittent electronic glitches
How to Fix
Fix the water-intrusion source first (reseal bulkhead gasket, reattach fresh-air vent, clear the A/C drain) before replacing electronics. A water-damaged BCM must be replaced and re-programmed with a proxy alignment (not plug-and-play); used modules often require harness re-pinning. Dry and inspect the footwell wiring loom.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- 3M 08612 Windo-Weld 3/8-inch round ribbon sealer, 15-foot kit
reseal the confirmed water-entry seam before BCM or harness remediation Fitment/availability: Universal sealing material only where water testing identifies a Giulia fresh-air inlet or nonstructural bulkhead seam specified for 3/8-inch n…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
On early-build 2018 Stelvios the joint where the A-pillar meets the HVAC box was not properly sealed at the factory. Water runs down inside the pillar and reaches the body control module and its connectors, corroding the pins. Because the BCM in this platform gates wipers, exterior lighting, turn signals, horn and interior lighting, a single corroded connector produces a scattershot list of unrelated electrical faults that owners and even dealers frequently misdiagnose as separate problems. This is the root cause behind a large share of the 'random electrical gremlins' reputation attached to the first model year specifically - it is a 2018 build-quality defect, not a characteristic of the later cars.
Common Symptoms
- Windshield wipers stop working or operate on their own
- Turn signals activate for no reason
- Horn inoperative
- Exterior lighting or headlights cut out
- Complete loss of interior lighting
- Multiple unrelated warning lights illuminated at once
- Dampness or water staining in the A-pillar or footwell area
How to Fix
Free recall remedy exists: NHTSA campaign 18V-205 (FCA campaign U36), recall opened April 25, 2018. Dealers apply additional sealing at the A-pillar/HVAC box joint to stop the water path. Note the recall seals the leak but does not by itself replace a BCM or connector already corroded - if faults persist after the sealing is applied, the module and its connectors must be inspected and replaced separately. Have the VIN checked on the NHTSA recall lookup before buying any 2018 car showing intermittent wiper or lighting faults.
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 Alfa Romeo?
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 Alfa Romeo it is documented across 2 models: Giulia, Stelvio.
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 Alfa Romeo?
Published repair estimates on Alfa Romeo range from $300 to $1,500 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 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.