Is It Safe to Drive With a U0140 Code?
Common Symptoms of a U0140 Fault
U0140 Symptoms at a Glance
Multiple warning lights
Central locking issues
Window operation problems
Lighting faults
EML on
Possible Causes of U0140
A U0140 code can be triggered by faults across several systems. Identifying the exact root cause requires proper diagnostic equipment and live data — not just reading the code.
Common Causes of U0140
CAN Bus Wiring to BCM
CAN bus wiring to the BCM is damaged.
BCM Power / Ground Fault
Poor power or earth connection to the BCM.
BCM Failure
The body control module itself has failed.
Battery Voltage Issue
Low voltage causing BCM communication loss.
Why we don't list the exact part: A U0140 code tells you what's happening but not why. Replacing parts based on the code alone is the most common way drivers waste money. A proper diagnosis identifies the specific cause first.
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U0140 and Your MOT
A stored U0140 fault code will cause your car to fail its MOT. The engine management light will be illuminated during the test — an automatic failure under current MOT standards. Even if the light temporarily clears, the code remains in ECU memory and can be read by testers.
Get the fault diagnosed and repaired first, then have the code cleared and confirm the light stays off before booking your MOT.