What it means
A control module has stopped receiving expected messages from rear entertainment control module B. The code identifies the communication loss; rear entertainment functions routed through that module may be affected.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
Rear entertainment control module B manages or routes the rear entertainment functions assigned to the B module and communicates status over the vehicle network. U0249 sets when another module stops receiving expected messages from rear module B, potentially interrupting those rear entertainment functions.
Common causes
Most likely first.
- Loss of power or ground to the module
- Open, shorted, or damaged network wiring or connector
- Failed module
Symptoms
- Rear entertainment functions may be unavailable or limited
- A warning may appear depending on the vehicle
How to diagnose it
- Scan all modules for communication codes and review event data for other network faults that may involve rear entertainment control module B.
- Check the rear entertainment functions assigned to module B and note any display, audio, or communication warning.
- Inspect module B's connectors and nearby wiring for looseness, damage, corrosion, or liquid intrusion.
- Check the rear module's power and ground circuits using the manufacturer's diagnostic procedure.
- Test the network wiring to rear entertainment control module B for opens, shorts, or poor connections using the wiring diagram.
- If its power, ground, and network circuits pass, follow manufacturer diagnostics to assess module B for internal failure.
Common fixes
- Reconnect or clean a loose or corroded rear entertainment module B connector.
- Repair damaged network wiring or connector terminals leading to module B.
- Repair a failed power or ground supply to the module.
- Replace rear entertainment control module B if diagnostics confirm internal failure.
Can I keep driving?
Driving is generally possible if the vehicle operates normally, though rear entertainment functions may be unavailable. Keep the driver's attention on the road and avoid trying to troubleshoot displays while moving.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.