U0140: Lost Communication with Body Control Module
Can you still drive? It depends. If headlights, brake lights, and basic engine controls work, you can drive cautiously to a shop. If lighting or critical controls are non-functional, have it towed.
What Does U0140 Mean?
Code U0140 indicates that one or more control modules have lost CAN bus communication with the Body Control Module (BCM). The BCM controls many convenience and safety features including lighting, door locks, windows, and security. Loss of BCM communication can cause widespread electrical symptoms throughout the vehicle.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Failed BCM
- BCM fuse or power supply failure
- CAN bus wiring damage near the BCM
- BCM connector corrosion
- Water damage from windshield or sunroof leak reaching the BCM
Symptoms
- Multiple interior and exterior lights not working
- Power windows inoperative
- Door locks not responding
- Security system malfunction
- Instrument cluster warnings
- Windshield wipers may not function
Diagnostic Steps
- 1Check BCM fuses and power supply circuits
- 2Attempt to communicate with BCM via scan tool
- 3Inspect BCM connector for corrosion or water damage
- 4Check for water leaks near the BCM location (often behind dash or kick panel)
- 5Verify CAN bus wiring integrity at the BCM connector
- 6Check BCM ground connections
Recommended Parts & Tools
BCM connector repair kit
automotive fuse assortment
dielectric grease
water leak detection kit
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $100 - $1200 |
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Chat with AI About U0140Commonly Affected Vehicles
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Frequently Asked Questions
What does the body control module control?
The BCM manages many vehicle functions including interior and exterior lighting, power windows, door locks, windshield wipers, security system, and often the horn and turn signals.
Can a water leak cause U0140?
Yes, water leaks from the windshield, sunroof, or A/C evaporator drain are a very common cause of BCM failure. The BCM is often located where water can pool.
Does a replacement BCM need programming?
Yes, a new BCM must be programmed to the vehicle. This typically requires dealer-level or advanced aftermarket programming equipment.
Community Fix Reports
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