U009C

Vehicle Communication Bus I Performance

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

~$278 (est.)

Symptoms

Illumination of the fault warning lamp (Check Engine)
Incorrect operation or shutdown of various vehicle systems (for example, cruise control, ABS)
Difficulty starting the engine or loss of power
Dashboard malfunctions
Additional related trouble codes appear

Causes

Open or short circuit in the CAN bus wires (CAN High / CAN Low)
Corrosion or poor contact in CAN connectors
Malfunction of one of the electronic modules (ECU) connected to the bus
Problems with power or grounding of any module
Damage to terminal resistors in the CAN network

How to Fix

Read all fault codes and check freeze frame data for U009C
Visually inspect the CAN bus wiring harness for damage and corrosion of the connectors
Check the resistance and voltage on the CAN High and CAN Low lines using a multimeter or oscilloscope
If a faulty module is identified (by sequentially disconnecting it), replace it
Clear code and test drive to verify troubleshooting

Related codes

U0100 U0101 U0121