Control Module Communication Bus Off
Loss of communication on the control module 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)
There’s a problem with the electrical signals sent between control modules. It’s like a bad phone line where modules can’t talk to each other properly.
What the computer is actually seeing
The computer detects no response or invalid signals from a control module it expects to communicate with, leading to critical functions being disabled.
What a healthy reading looks like
Normal communication should show a proper response and voltage levels between 2.5V and 5V between modules on the CAN bus at all times during operation.
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.
- 1Check the wiring and connectors for the affected control module—look for frays, corrosion, or pin damage. Decision: If issues found, repair or replace the wiring/connector; if none, proceed to step 2.
- 2Verify the vehicle battery voltage. It should be between 12.4V and 14.5V with the engine running. Decision: If voltage is low, charge/replace the battery; if normal, proceed to step 3.
- 3Perform a communication check using a scan tool to see which modules are not responding. Decision: If a specific module is unresponsive, replace that module; if all respond intermittently, further investigation of the CAN bus is needed.
Common causes
- Faulty wiring or connectors in the communication circuit
- Damaged control module
- Corrosion in connectors
- Battery voltage issues affecting module operation
Typical repair cost
$$
Related codes
Frequently asked questions
Can I still drive the vehicle?
No, this code can lead to a loss of critical functions. It's best to diagnose and repair before driving.
Will this code come back after clearing?
If the underlying issue isn't fixed, yes, it will likely return.
Can this affect other systems like brakes or transmission?
Yes, since modules communicate for proper functionality, it can impact safety and drivability.
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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