Controller Area Network (CAN) Message Fault
There is a problem with the CAN communication between the engine control module and another module.
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 truck's computer can't talk properly with another module, like the transmission or brakes, which can lead to major issues.
What the computer is actually seeing
The engine control module (ECM) is failing to receive expected messages from another module on the CAN bus, indicating communication problems.
What a healthy reading looks like
A properly functioning CAN bus should show signal voltages between 2.5V (idle) and 1.5V (active) on the high and low lines respectively, with a maximum message response time under 10 milliseconds.
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 wiring and connectors related to the CAN bus for any visible damage or corrosion.
- 22. Check for proper ground connections; ensure all modules share a good common ground. Correct if necessary.
- 33. Use a multimeter to test for voltage levels on the CAN high and low wires; both should be within expected values (2.5V idle) under normal conditions. If off, identify the fault in wiring.
- 44. Perform a scan with a compatible diagnostic tool and check for additional fault codes that may indicate where the issue lies; address those as needed.
- 55. If wiring and connectors are good, suspect the control module(s) involved; consider swapping with a known-good unit if available.
- 66. Clear codes and perform a vehicle test to see if the code returns after fixes; if it does, further investigation into other modules or wiring may be necessary.
Common causes
- Faulty wiring or connectors in the CAN network
- Failing control module (like ECM or TCM)
- Poor ground connections or power supply issues
- Corrosion or damage at interfaces
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, it is not safe to drive until this issue is fixed, as it can lead to loss of control functions.
Will this code come back after I clear it?
If the underlying issue isn't fixed, yes, expect it to return immediately or soon after.
Why does this code sometimes pair with others?
It often pairs with other communication fault codes indicating multiple failing modules on the same CAN network.
Working a real vehicle right now?
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