Damaged or disconnected wiring or connector at the left front distance sensor; Failed left front distance sensor (internal fault or contamination); Corrosion or water intrusion in the sensor connector or harness; Software or calibration issue in the sensor or control module; Faulty control module that processes the sensor data (e.g., driver assist module); Physical damage to the sensor from road debris or minor impact; Electrical interference or voltage supply issues affecting the sensor circuit

DTC codes / U04xx · Invalid data received from a module / U043B

U043BInvalid Data Received From Front Distance Range Sensor - Left

U043B is a communication fault indicating that a control module received invalid or missing data from the front distance range sensor on the left side of the vehicle. The computer detected that the sensor's messages were either absent, corrupted, or outside expected parameters, so it flagged the data as invalid.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaInvalid data received from a module

Symptoms you may notice

A warning light on the dashboard, often the forward collision or parking assist icon
The forward collision warning system may be disabled or show a fault message
Adaptive cruise control may not engage or may disengage unexpectedly
Parking assist features may stop working or give false alerts
Often no symptoms besides the warning light, with the vehicle driving normally
In some cases, the vehicle may enter a reduced power or limp mode if the fault affects safety systems

Common causes, most likely first

Damaged or disconnected wiring or connector at the left front distance sensor
Failed left front distance sensor (internal fault or contamination)
Corrosion or water intrusion in the sensor connector or harness
Software or calibration issue in the sensor or control module
Faulty control module that processes the sensor data (e.g., driver assist module)
Physical damage to the sensor from road debris or minor impact
Electrical interference or voltage supply issues affecting the sensor circuit

How to diagnose and fix it

Inspect the left front distance sensor and its connector for visible damage, corrosion, or loose pins
Check the sensor wiring harness for chafing, breaks, or poor ground connections
Use a scan tool to read live data from the sensor and verify if it is communicating at all
Perform a visual inspection of the sensor face for dirt, mud, or snow buildup and clean if necessary
Test the sensor circuit with a multimeter for power, ground, and signal integrity
If wiring is good, substitute a known-good sensor to see if the code clears
After repair, clear codes and perform any required calibration or relearn procedure for the driver assist system

What the left distance sensor code hides

A dirty or obstructed sensor face can cause invalid data without any physical damage, so always clean the sensor before condemning it.
The code often sets after a low-voltage event or battery replacement, and may clear after a few drive cycles if the sensor reinitializes correctly.
A faulty ground connection shared with other sensors can corrupt the data signal, so check grounds before replacing the sensor.
Some vehicles require a calibration drive or static target setup after sensor replacement, and skipping this step will set the code again.
The left front distance sensor may be part of the blind spot monitoring system on some models, so related codes like U043A or U043C may also appear.

Can I keep driving with U043B?

The vehicle is generally safe to drive because the fault affects driver assist features, but avoid relying on adaptive cruise control or forward collision warning until repaired. If the warning light is accompanied by reduced power or braking assist loss, have the vehicle inspected immediately.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.