CAN Communication Bus Fault
There is a communication issue on the CAN bus.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
Your car's computer system is trying to talk to other modules, but something is blocking or interrupting that communication.
What the computer is actually seeing
The computer is detecting that a particular module on the CAN bus is not responding or is providing inconsistent data during a communication check.
What a healthy reading looks like
CAN bus voltage should be around 2.5V to 3.5V with proper communication from all nodes.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the battery voltage; it should be between 12.4V and 12.8V with the engine off. Is it within range? (Yes: proceed, No: charge or replace battery)
- 22. Inspect the wiring and connectors related to the CAN bus. Are they intact and corrosion-free? (Yes: proceed, No: repair or replace damaged wiring/connectors)
- 33. Measure the CAN bus voltage with a multimeter. Is it between 2.5V and 3.5V? (Yes: proceed, No: repair short/open in the CAN bus)
- 44. Check for additional fault codes using a scan tool. Are there other related codes? (Yes: diagnose those first, No: continue)
- 55. Swap suspected faulty module with a known good one, does the code persist? (Yes: further diagnose wiring, No: replace the swapped module)
Common causes
- Loose or corroded connectors on the CAN bus
- Damaged wiring in the CAN bus circuit
- Faulty control module(s) on the bus
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It may be drivable, but you could lose functionality in other systems; it's best to fix it soon.
Will this code come back after clearing?
If the underlying issue isn't resolved, yes, it will likely return.
Why do I see this code with others like U0140?
These codes often appear together because they all relate to communication issues on the CAN bus.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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