OBD codes / U0140
U0140
ModerateLost Communication With Body Control Module
U0140 usually isn't an immediate safety emergency, but the body module handles lights, wipers, and security — so failures can be inconvenient or unsafe at night or in rain, and some cars may refuse to start if the immobilizer is caught up in it. Get it diagnosed promptly, and confirm your headlights, brake lights, and wipers work before driving.
What this code means
U0140 means other computers lost contact with the body control module (BCM) — the computer that runs things like lights, wipers, power windows, locks, and often key/security functions. As with all U-codes this is a network fault, not proof the BCM is dead: check for blown fuses or a lost power feed to the module, corroded connectors and grounds, and damaged network wiring before suspecting the module itself. Low battery or charging voltage is a classic cause of phantom communication codes and is the first, free check. Symptoms can be strange and scattered — flaky interior electronics, warning lights, sometimes security-system quirks that prevent starting — because the BCM touches so many small systems. Diagnosis means confirming the BCM has power, ground, and an intact data connection.
Symptoms you might notice
- Erratic behavior of lights, wipers, locks, or windows
- Multiple warning lights on the dash
- Security/immobilizer quirks, sometimes a no-start
- Other lost-communication codes stored alongside
What it costs to fix
Varies by vehicle — get it diagnosed.
The repair cost for this code depends too much on your exact vehicle and the underlying cause to quote a meaningful range. Confirm the cause first so you only pay for the fix you actually need.
Diagnose U0140 for my vehicle →Frequently asked
Can I drive with U0140?
Usually yes for short trips, provided your lights and wipers work — check them before setting out. The risks are losing convenience and visibility systems, and on some cars security functions can interfere with starting.
What does the body control module actually do?
It's the computer behind most non-engine electrics: exterior and interior lights, wipers, power windows and locks, and often the security/immobilizer system. That's why symptoms of losing it look like scattered electrical gremlins rather than an engine problem.
Is U0140 an expensive fix?
It depends entirely on the cause. A fuse, ground, or connector is cheap; harness repairs are moderate; a replacement BCM with programming is the costly end. Diagnosis has to sort that before anyone can quote fairly.
Should I check my battery first?
Yes — weak batteries and poor grounds are notorious for causing phantom lost-communication codes across multiple modules. Verify battery and charging voltage before spending anything on parts.
Seeing U0140 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose U0140 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like U0140 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.