U02B8 code meaning
Lost Communication With Rear Radar Module C
What U02B8 means
A third rear radar is only fitted where the usual left and right corner pair is extended, for instance by a sensor watching straight back or along a long body. No manufacturer documents U02B8 publicly or states where module C sits, and its invalid-data partner U05B9 is equally unpublished. The documented rear letters belong to the corner pair: Mercedes-Benz gives A to the left and B to the right outer sensor at the back of its 2026 CLA electric. U02B8 means module C has dropped off the bus, so functions that rely on its field of view, typically cross traffic or exit warnings, lose part of their coverage while the corner units may keep working. Check its connector and supply first, then the module; after replacement the radar usually needs calibration.
U02B8 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U02B8
- Rear assistance functions partly unavailable, assistance message
- Cross traffic or exit warning restricted
Common causes of U02B8
- Most likelyConnector or wiring of radar C damaged or unplugged
- PossibleSupply or ground of radar C missing
- PossibleRear radar C failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Rear radar module cVehicle bus wiring
What each part of U02B8 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B8 | The exact fault in that area. |
What to do next
- Note U02B8 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 U02B8
What does U02B8 mean?
U02B8 means "Lost Communication With Rear Radar Module C". A third rear radar is only fitted where the usual left and right corner pair is extended, for instance by a sensor watching straight back or along a long body. It is a generic code, so it means the same on every make.
Is it safe to drive with U02B8?
U02B8 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U02B8 fail an emissions test?
U02B8 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 U02B8 to fix?
Difficulty: hard. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U02B8 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.