U0065: Vehicle Communication Bus E Performance

What it means

Vehicle communication bus E performance is outside the monitored range. The code does not identify a specific cause.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

Vehicle communication bus E carries messages between its connected modules. U0065 means the control module has detected bus E performance outside its monitored range, which can reflect unstable or degraded communication rather than a specified open or short.

Common causes

Most likely first.

1. Wiring chafed or marginal
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Record all module codes and freeze-frame details, including when the bus E performance fault occurred and whether it is intermittent.
2. Check which bus E modules report faults or drop communication, and compare their records for a shared pattern.
3. Inspect bus E wiring, connectors, and splices for chafing, loose terminals, corrosion, or movement that could make the fault intermittent.
4. Use the manufacturer's procedure to monitor bus E communication and test its conductors and termination while reproducing the conditions in the freeze-frame data.
5. Check gateway routing after wiring, connections, and termination are within the manufacturer's specification.

Common fixes

• Secure or repair chafed bus E wiring causing intermittent communication.
• Clean, tighten, or replace loose or corroded bus E connector terminals.
• Correct a termination fault if testing shows it is outside the manufacturer's specification.
• Repair or replace the gateway only if testing confirms incorrect routing is degrading bus E performance.

Can I keep driving?

If affected features work normally, limit unnecessary trips and watch for intermittent warnings or function loss; bus E communication can deteriorate and affect connected modules. Stop if an essential system becomes unreliable.