Faulty or failing Driver Monitoring System module; Corroded, loose, or damaged wiring or connectors in the DMS circuit; Software or firmware corruption in the DMS module or receiving module; Network communication bus issues, such as a shorted or open data line; Low voltage or poor ground connection affecting the DMS module; Aftermarket accessories or modifications interfering with the DMS signal; Internal failure in the receiving module that misinterprets valid data

DTC codes / U05xx · Network communication / U05B4

U05B4Invalid Data Received From Driver Monitoring System Module

Q: What does code U05B4 mean?

Invalid Data Received From Driver Monitoring System Module. U05B4 is a communication fault indicating that a control module received invalid or corrupted data from the Driver Monitoring System (DMS) module over the vehicle's network. The DMS module is responsible for tracking driver attention and alertness, and when its data fails validation, the receiving module sets this code and may disable related driver-assist features.

U05B4 is a communication fault indicating that a control module received invalid or corrupted data from the Driver Monitoring System (DMS) module over the vehicle's network. The DMS module is responsible for tracking driver attention and alertness, and when its data fails validation, the receiving module sets this code and may disable related driver-assist features.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Illumination of the check engine light or a dedicated driver-assist warning light
Driver attention or drowsiness warnings may become unavailable or behave erratically
Other advanced driver-assistance systems (ADAS) features such as lane keeping or adaptive cruise may be disabled
Intermittent or no symptoms besides the warning light, especially if the fault is stored but not currently active
Possible message on the dashboard indicating a camera or sensor fault

Common causes, most likely first

Faulty or failing Driver Monitoring System module
Corroded, loose, or damaged wiring or connectors in the DMS circuit
Software or firmware corruption in the DMS module or receiving module
Network communication bus issues, such as a shorted or open data line
Low voltage or poor ground connection affecting the DMS module
Aftermarket accessories or modifications interfering with the DMS signal
Internal failure in the receiving module that misinterprets valid data

How to diagnose and fix it

Use a scan tool to retrieve all stored codes and freeze-frame data, and verify battery voltage and ground integrity
Inspect the DMS module connectors and wiring for corrosion, looseness, or damage, and repair as needed
Check for technical service bulletins (TSBs) or software updates for the DMS module and apply if available
Perform a voltage drop test on the DMS power and ground circuits to rule out resistance issues
Substitute a known-good DMS module or reflash the existing module with the latest calibration
Clear codes and perform a road test to verify the repair, monitoring live data for DMS communication

When the driver monitor lies to the network

A weak or failing battery can cause the DMS module to send corrupted data, so always load-test the battery before condemning the module.
The code often sets intermittently due to a poor ground connection at the DMS module, which is easily overlooked during visual inspection.
Aftermarket dash cams or phone mounts placed near the DMS camera can obstruct its view and trigger invalid data, mimicking a module failure.
Some vehicles require a calibration procedure after DMS module replacement or windshield work, and skipping it can cause this code to return.
The receiving module may be the actual culprit if it fails to process valid DMS data, so swapping the DMS module without testing the network is a misdiagnosis trap.

Can I keep driving with U05B4?

The vehicle remains safe to drive because the fault primarily affects driver-assist features, but you should avoid relying on those systems until the issue is repaired. If the warning light is accompanied by other communication codes or drivability symptoms, have the vehicle inspected promptly.

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.