Question 1

What does fault code U0140 actually mean?

Accepted Answer

U0140 is a network communication fault code. It means one or more control modules on your vehicle's CAN (Controller Area Network) bus have lost the ability to communicate with the Body Control Module (BCM). The BCM is the central hub for body electronics — locks, lights, wipers and more — so when communication drops, multiple systems can misbehave simultaneously.

Question 2

Is it safe to drive with a U0140 code in North London?

Accepted Answer

It depends on which symptoms are active. If your indicators, brake lights or wipers are affected, the vehicle is not roadworthy and you should not drive it on North London roads. Central locking failure alone is less immediately dangerous but should still be investigated promptly, as an intermittent fault can escalate. Call us on 020 8803 1231 for honest advice.

Question 3

How much does U0140 diagnosis cost at MnF Motors?

Accepted Answer

Our electrical diagnostic sessions start from £65. This covers a full scope-level CAN bus inspection, not just a code read. Once we have identified the root cause — whether that is a wiring fault, a failed earth, or a BCM module issue — we provide a fixed-price repair quote before any work begins. No hidden extras.

Question 4

Can a failed earth really cause U0140?

Accepted Answer

Yes — and it is one of the most common causes we find in North London vehicles. A poor earth connection can corrupt CAN bus voltage levels, causing the BCM to appear offline to other modules on the network. This is exactly why we use oscilloscope-level diagnosis: a simple code reader cannot tell you whether the fault is the BCM itself, the wiring harness, or a corroded earth strap.

Question 5

Do you offer any warranty on U0140 repairs?

Accepted Answer

Yes. All electrical repairs at MnF Motors carry a parts and labour warranty. If you have an existing extended warranty policy, visit our Warranty Claims page — we work with many warranty providers and can advise on what is covered before you commit to a repair.