OBD-II Code · Network
U0140
Lost Communication with Body Control Module
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$400–$1,500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
BCM comm lost.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Most body electronics dead
- Warning lights
Likely causes
- Failed BCMMost common
- Wiring
- Power/ground
Read the full diagnostic procedureU0140 is loss of communication with the Body Control Module (BCM), which on modern vehicles is the central gateway for interior electronics, lighting…
U0140 is loss of communication with the Body Control Module (BCM), which on modern vehicles is the central gateway for interior electronics, lighting, locks, wipers, and often the CAN gateway between the high-speed powertrain bus and the low-speed body bus.
Cheapest-first
- a U0140 with multiple other U-codes (U0100, U0121, U0155) usually means the BCM-gateway is dead, not that every module is dead individually.
- Check BCM power feeds (often three or four separate fuses for ignition, battery, and accessory) and verify the BCM has clean ground at its case-mount bolt.
- Back-probe both the high-speed CAN-H/CAN-L and the low-speed bus pins at the BCM connector, looking for 2.5V idle on each CAN leg; the low-speed bus (GMLAN single-wire, LIN, or Chrysler PCI) has different voltage signatures and a scope is required to confirm activity.
- Verify 60 ohms across the high-speed bus with key off.
- BCMs are programmed to VIN on virtually every platform 2006+, so a junkyard swap without dealer or J2534 reflash will throw U0140 indefinitely.
- Throwing a $400-$900 BCM at the problem before checking fuse F31 or a stuck door-lock actuator dragging the body bus down is the classic expensive misstep.
Vehicle-specific patterns2007-2014 Chrysler/Dodge/Jeep with TIPM (which is the BCM/gateway combined) is the textbook U0140 generator; failed TIPMs cause no-start, dead instru…
- 2007-2014Chrysler/Dodge/Jeep with TIPM (which is the BCM/gateway combined) is the textbook U0140 generator; failed TIPMs cause no-start, dead instrument cluster, and rolling U-code storms.
- 2007-2013GM trucks with GMLAN see U0140 when a single corroded door-harness boot at the A-pillar shorts the single-wire bus to ground, often after dealership tint installs.
- 2008-2013Ford F-Series with SJB (Smart Junction Box) sets U0140 from water intrusion at the kick panel after windshield reseals or A-pillar leaks.
- 2007-2010BMW E60/E90 has U0140 trace to the FRM (Footwell Module) bricking from low battery during programming or jump-starts.
Estimated repair$60 to $1500.
Look up another code
U0140 — frequently asked
What does a U0140 code mean?
BCM comm lost.
What causes a U0140 code?
Common causes: Failed BCM; Wiring; Power/ground.
What are the symptoms of a U0140 code?
Typical symptoms: Most body electronics dead; Warning lights.
Is it safe to drive with a U0140 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $400-$1,500.
How do I diagnose a U0140 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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