U0297: Lost Communication With AC/DC Converter Control Module B

What it means

The hybrid CAN has lost the hybrid powertrain control module. Hybrid operation is disabled and the vehicle defaults to combustion-only mode if available.

At a glance

• Usually lights the warning light of the system that lost communication
• The engine or gearbox may go into limp mode

How it works

AC/DC converter control module B is a separately identified converter node on the vehicle network. This code sets when other modules stop receiving expected messages from module B; the affected converter function may be unavailable, though the exact charging or power effect depends on the vehicle's design.

Common causes

Most likely first.

1. Hybrid module unpowered
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. Scan all modules for freeze-frame and charging or power-conversion codes, and identify which modules report converter control module B missing.
2. Check the vehicle's charging behavior and warning messages to establish which function associated with module B has stopped, without assuming it is the onboard AC charger.
3. Inspect module B's accessible low-voltage connector and harness for looseness, corrosion, moisture or damage; avoid contact with high-voltage components.
4. Check the module's specified power and ground, then test its network wiring and gateway path for opens, shorts or poor connections using manufacturer procedures.
5. If supplies and wiring are sound, use manufacturer diagnostics to assess module B and network termination; any high-voltage checks should be handled by qualified personnel.

Common fixes

• Repair a loose, corroded or damaged low-voltage connector serving converter control module B.
• Repair an open or short in the network wiring to module B.
• Restore module B's specified power or ground by repairing the confirmed feed, fuse or ground fault.
• Correct a gateway routing fault if testing confirms it blocks module B messages.
• Repair a network termination fault or replace module B only when manufacturer testing confirms the cause.

Can I keep driving?

Limit driving to what the vehicle's remaining propulsion and charging capability safely supports, and heed any reduced-power or battery warnings. If the vehicle cannot maintain safe propulsion or charge is insufficient for the trip, stop safely and arrange recovery.