CAN Communication Failure
Lost communication with Engine Control Unit (ECU).
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 ECU isn't getting or sending expected signals, which can happen if wiring is damaged or connectors are loose.
What the computer is actually seeing
The system notices a drop in the CAN bus voltage below 0.5V or that no data packets are being transmitted for a set amount of time, usually around 500 milliseconds.
What a healthy reading looks like
CAN bus voltage should be between 2.5V to 5.0V when the system is active; data packets should be transmitted every 10-20 milliseconds under normal 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.
- 11. Inspect the wiring and connectors related to the CAN bus for signs of damage or corrosion.
- 22. Measure the voltage on the CAN bus; it should be between 2.5V and 5.0V.
- 3 - If voltage is outside this range, repair any damaged wiring.
- 43. Check for loose connectors and reseat if necessary; clear the codes and test drive.
- 5 - If the code comes back, proceed to the next step.
- 64. Use a scan tool to monitor data transmission from the ECU; look for missing or irregular data packets.
- 7 - If data issues persist, consider swapping the ECU with a known good unit for a quick test.
Common causes
- Corroded or damaged wiring in the CAN bus system
- Loose or damaged connectors
- Faulty ECU or other modules on the bus
- Interference from electrical accessories
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It may be drivable, but expect potential stalling or performance issues; it's recommended to fix soon.
Will this fault code return after clearing?
Yes, if the underlying issue isn't addressed, the code will reappear.
Why does this code show up with other codes?
Multiple codes can indicate a failure in the communication network, so fix the main issue first.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →