C1298: OBD-II code C1298 flags a Class 2 serial data link fault between the PCM and the EBCM — they have lost normal communication with each other.

Symptoms

• ABS, traction control, and stability control lamps illuminate together, and multiple U-codes are typically stored on both modules.
• Traction control and stability interventions are disabled because torque coordination between EBCM and PCM is impossible.
• The vehicle may run in a limp mode with reduced engine performance until the bus is restored.

Common causes

• A damaged Class 2 serial data bus wire, a bad splice, or a shorted section between the PCM and the EBCM.
• A completely failed PCM or EBCM that is either not responding or flooding the bus with invalid traffic.
• A defective node elsewhere on the bus (BCM, cluster) dragging the bus down and preventing normal PCM-EBCM communication.

What to do?

Scan every module on the vehicle for U-codes to isolate which node is at fault. Measure Class 2 bus voltage and resistance per the service manual. Disconnect suspect modules one at a time to isolate the offending node. Repair wiring or replace the failed module and reprogram.