U02B3 code meaning
Lost Communication With Driver Monitoring System Module
What U02B3 means
The driver monitoring module evaluates an interior camera that follows where the driver looks, how open the eyes are and how the body is held, to judge distraction and drowsiness; the EU's General Safety Regulation makes distraction warning mandatory on all new vehicles from July 2026. U02B3 is logged when this module stops talking to the network. No manufacturer documents U02B3 publicly. Subaru runs a separate DMS control unit on the 2019-2020 Forester and 2020 Legacy and Outback that also stores up to five driver profiles, which technicians back up with SSM4 before service (bulletin 07-175-20). Stellantis names a DMSM among the ADAS modules of the 2022-2025 Grand Cherokee and asks for 90 % battery charge and a 10-minute bus sleep after a deep discharge. Attention warnings and hands-off functions are then lost.
U02B3 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U02B3
- Driver attention or drowsiness warning unavailable
- Hands-free or lane assistance switched off with a service message
- Stored driver profiles not recognised
Common causes of U02B3
- Most likelyDeep battery discharge or replacement left the module offline
- PossibleConnector at the camera or module loose, e.g. after steering column or dash work
- PossibleDriver monitoring module or camera failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Driver monitoring moduleVehicle bus wiring
What each part of U02B3 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B3 | The exact fault in that area. |
What to do next
- Note U02B3 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U02B3
What does U02B3 mean?
U02B3 means "Lost Communication With Driver Monitoring System Module". The driver monitoring module evaluates an interior camera that follows where the driver looks, how open the eyes are and how the body is held, to judge distraction and drowsiness; the EU's General Safety Regulation makes distraction warning mandatory on all new vehicles from July 2026. It is a generic code, so it means the same on every make.
Is it safe to drive with U02B3?
U02B3 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U02B3 fail an emissions test?
U02B3 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U02B3 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. This is a job for a workshop.
Will U02B3 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.