U0140: Lost communication with the body control module (BCM)
The network is not receiving messages from the body control module, which runs lights, locks, wipers and more. Often power, ground or a connector.
| Code | U0140 |
|---|---|
| System | Communication network |
| Group | U01xx, Lost communication with control units |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What U0140 means
The body control module (BCM) looks after many cabin functions: lights, indicators, central locking, wipers, electric windows and sometimes the immobiliser. This code means it has stopped talking to the other control units over the data network. Because it does so much, the symptoms can vary widely.
Most common causes
- Low battery or loose terminals
- Blown power fuse for the body control module
- Loose, corroded or damp connector on the module (often from water leaking through the windscreen or blocked drains)
- Poor ground on the module
- Damaged network wiring
- Faulty body control module or a programming fault
Symptoms
- Lights, indicators or wipers failing or staying on
- Central locking or remote key not responding
- Various warnings on the dashboard
- Battery drain with the car parked
- On some cars, no start
Can you drive with U0140?
With care You can drive if lights, indicators and wipers work, but take care. Get it seen soon, as it can leave you without lights or unable to start.
Open the bonnetthe in-depth explanation
How to check it
Before going to the garage, test lights, indicators, wipers and locking so you can tell them exactly what fails. Also look for damp carpets in the driver or passenger footwell, where this module often sits.
How to read and clear U0140 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see U0140 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- U0137 The trailer brake control unit is not answering on the car network
- U0139 The suspension control unit B is not answering on the car network
- U013C The accelerator pedal module is not answering on the car network
- U013F The pedestrian alert control unit is not answering on the car network
- U0141 Lost communication with body control module A
- U0142 The body control unit B is not answering on the car network
- U0143 The body control unit C is not answering on the car network
- U0144 The body control unit D is not answering on the car network
- U0100 Lost communication with engine control module (ECM/PCM A)
- U0101 Lost communication with transmission control module (TCM)
- U0102 Lost communication with transfer case control module
- U0103 Lost communication with the gear shift module
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: Lighting.
What does code U0140 mean?
The body control module (BCM) looks after many cabin functions: lights, indicators, central locking, wipers, electric windows and sometimes the immobiliser. This code means it has stopped talking to the other control units over the data network. Because it does so much, the symptoms can vary widely.
Can you drive with U0140?
You can drive if lights, indicators and wipers work, but take care. Get it seen soon, as it can leave you without lights or unable to start.
How do you clear U0140?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, U0140 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
