U043B code meaning
Invalid Data Received From Front Distance Range Sensor - Left
What U043B means
U043B covers the left front distance sensor, usually a short-range corner radar that widens the view of adaptive cruise and collision assistance beyond the central long-range unit; that one has U0433, the right corner U043C. A receiver sets U043B when the left sensor's object or status frames arrive but fail plausibility or protection checks. No manufacturer documents U043B publicly. GM's 2025 EOCM3 tables list only the lost-contact partner U023D for the left front short-range radar: frames absent longer than 0.2 s end adaptive cruise (special Type C), which indicates how the assistance controller is likely to react to corrupted data as well. Expect assistance features reduced or switched off and a prompt to clean or check the sensor area.
U043B at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.4 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U043B
- Adaptive cruise or lane change assistance unavailable
- Message to clean or check front sensors
Common causes of U043B
- PossibleLeft corner radar misaligned or damaged after a bumper impact
- PossibleCorner radar software not matching the assistance controller
- Less likelyMoisture or corrosion in the left sensor connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Front distance sensor left
What each part of U043B means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3B | The exact fault in that area. |
What to do next
- Note U043B 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 U043B
What does U043B mean?
U043B means "Invalid Data Received From Front Distance Range Sensor - Left". U043B covers the left front distance sensor, usually a short-range corner radar that widens the view of adaptive cruise and collision assistance beyond the central long-range unit; that one has U0433, the right corner U043C. It is a generic code, so it means the same on every make.
Is it safe to drive with U043B?
U043B does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U043B fail an emissions test?
U043B 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 U043B to fix?
Difficulty: workshop only. A typical repair takes 0.4 to 2.5 hours of work. This is a job for a workshop.
Will U043B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.