What it means
The vehicle bus reports loss of communication with the driver monitoring system (DMS) module. Eye/head-pose tracking for drowsiness, distraction and hands-on detection is unavailable, and dependent ADAS handover features may be inhibited.
How it works
The driver monitoring system module processes camera or sensor information about the driver's attention and reports its status over the vehicle network. The vehicle monitors those messages; U02B3 sets when they stop arriving, making driver attention features and some dependent assistance functions unavailable.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
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
- Scan driver-assistance and body modules for communication codes, and review freeze-frame data for when the driver monitoring module stopped reporting.
- Check the instrument panel for driver monitoring warnings and verify whether attention or hands-on alerts are unavailable.
- Inspect the module's connector and accessible network wiring for looseness, damage, or corrosion.
- Check the module's power and ground circuits using the manufacturer's procedure.
- Test its network wiring for an open, short, or poor connection using the manufacturer's procedure.
- If wiring, power, and ground pass, use the manufacturer's diagnostics to confirm whether the driver monitoring module has failed.
Common fixes
- Reconnect or clean the driver monitoring module connector.
- Repair damaged network wiring to the driver monitoring module.
- Restore the module's power or ground supply.
- Replace the driver monitoring module if testing confirms it has failed.
Can I keep driving?
You may lose drowsiness, distraction, or hands-on alerts, and dependent assistance features may be limited. Drive attentively and do not rely on those features until they are restored.
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.