Controller Area Network (CAN) Communication Failure
Loss of communication 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)
The engine control module (ECM) isn't getting messages from other modules on the vehicle’s CAN bus, which is a network that allows them to talk to each other.
What the computer is actually seeing
The ECM monitors the status of the CAN communication bus. If it doesn't receive expected messages within a certain time frame, it triggers this fault code.
What a healthy reading looks like
Messages should be received every few milliseconds. If no messages are detected for over 200ms, the code is set.
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. Inspect the CAN bus wiring and connectors for physical damage or corrosion. If damaged, repair or replace as needed.
- 22. Check for proper battery voltage (12V to 14V) at the ECM and TCM. If voltage is low, repair charging or wiring issues.
- 33. Use a scan tool to check if other codes are present that may indicate issues with specific modules on the bus. If yes, focus on those first.
- 44. Test the continuity of the CAN high and CAN low wires between the ECM and TCM. If either wire shows an open circuit, repair the wiring as needed.
- 55. If communication issues persist after repairs, consider swapping the ECM with a known good unit to see if the problem resolves.
Common causes
- Damaged wiring or connectors in the CAN bus
- Faulty ECM
- Failed transmission control module (TCM)
- Intermittent communication due to bad grounds or power supply
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Not recommended. Loss of communication can lead to reduced engine performance or even stalling.
Will the code come back after I clear it?
If the underlying issue isn't fixed, it will reappear after some driving.
Why does this code sometimes pair with transmission issues?
If the TCM isn't communicating, it can cause transmission performance problems.
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