Controller Area Network (CAN) Transmission Error
Indicates there is a problem with 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 vehicle's computer is not getting information from another control unit because there's a breakdown in communication, like a bad connection or wiring issue.
What the computer is actually seeing
The computer monitors the CAN bus communication for signals from various modules, expecting regular uploads of data packets. If it sees too many errors or fails to receive data, it flags SPN 1935.
What a healthy reading looks like
Normal communication on the CAN bus should show less than 5% error rate of transmitted packets. Voltage levels on the CAN High wire should be around 2.5V at idle and CAN Low should be near 2.5V as well, fluctuating when buses are active.
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 CAN bus wiring for visible damage or corrosion, especially connectors. Repair if necessary.
- 22. Inspect the resistance in the CAN wires. Each wire should measure between 60 to 120 ohms. If not, replace the affected section of wiring.
- 33. Verify ground and power connections to the affected control module, ensuring good voltage levels (around 12 volts) and a solid connection.
- 44. Use a scan tool to check for additional codes from other modules. If related codes are present, focus on those first.
- 55. If no issues found in wiring or connectors, swap the suspected faulty control module with a known good one and test the system.
Common causes
- Wiring issues in the CAN bus
- Faulty connectors or terminals
- Malfunctioning control module
- Short circuits or open circuits in the harness
- Interference from other electronic devices
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive if I get this code?
It's generally safe to drive, but you may experience issues with certain electrical systems or modules in the vehicle.
Will this issue come back after clearing the code?
If the underlying cause isn't fixed, the code will likely return after some time.
Why does this issue often pair with other fault codes?
Multiple codes can show up because several modules communicate over the CAN bus; a failure in one can affect others.
Working a real vehicle right now?
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