U0092: CAN Communication Bus C Performance

What it means

Bus C shows degraded performance with elevated error counters but has not yet gone bus-off. Sporadic message losses on modules attached to Bus C.

At a glance

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

How it works

CAN bus C carries messages among the modules attached to that network, and the gateway may route messages to other vehicle networks. U0092 indicates degraded bus C communication, with elevated error counts and sporadic message loss even though the bus has not gone bus-off.

Common causes

Most likely first.

1. Marginal Bus C wiring or connector
2. One module on Bus C transmitting marginal frames
3. Gateway module routing CAN messages incorrectly

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. Scan all modules for bus C communication codes and record which modules report errors or drop offline, since that can identify a shared wiring section or one troublesome node.
2. Review freeze-frame and live network data, including bus C error counters and module communication status, to see whether errors rise with specific operating conditions.
3. Inspect bus C wiring, connectors, splices, and grounds for looseness, corrosion, damage, or marginal contact, paying attention to the section shared by affected modules.
4. Use the manufacturer's procedure to test bus C wiring integrity and termination, and check for abnormal signal quality or error counts.
5. If the harness checks out, isolate bus C modules one at a time and assess gateway routing to find a transmitter or gateway causing degraded messages.

Common fixes

• Secure or clean a loose or corroded bus C connector.
• Repair damaged or marginal bus C wiring or a poor splice.
• Correct a bus C termination fault confirmed by testing.
• Repair or replace the module transmitting faulty frames or the gateway with a confirmed routing fault.

Can I keep driving?

Intermittent message loss can trigger warning lights, disable functions, or cause affected modules to reduce operation or shut down. Avoid driving if powertrain control or another safety-critical function is unreliable.