U05B9

Code

Generic U — Network/User

Invalid Data Received From Rear Radar Module C

Brand: Generic

Type: U — Network/User

Views: UK: 27 EN: 39 RU: 23

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Page language: EN

Faulty rear radar module (Module C) producing invalid messages
Intermittent or failed CAN/LIN communication between radar module and network
Damaged, corroded or loose connector or wiring to the radar module
Low or unstable supply voltage or poor ground at the radar module
Software mismatch, corrupted firmware, or required module programming/calibration missing
Interference on the data bus or multiple modules sending conflicting data

Malfunction indicator or ADAS warning illuminated (e.g., radar/parking sensors/driver assist warning)
Loss or degradation of rear radar-based features (blind spot detection, cross-traffic alert, rear collision mitigation)
Stored U05B9 with related communication or radar codes present
Intermittent or constant fault appearance depending on wiring/connector condition
Possible sporadic or constant false alerts from radar systems

Use a scan tool to read and record U05B9 and any related codes and freeze-frame data
Check for Technical Service Bulletins (TSBs) or software updates for rear radar modules
Visually inspect radar module C and its connector for damage, corrosion, water ingress, or loose retention
Inspect harness along its route for chafing, pinching, or recent body repairs that could have disturbed wiring
Verify fuses, relays, and power distribution feeding the radar module
Check other modules on the same bus for communication errors or similar invalid-data faults

Module supply voltage at connector: nominal battery voltage 11–14.5 V (measure with ignition ON per vehicle procedure)
Module ground: continuity to chassis ground, low milliohm resistance
CAN bus idle voltages: CAN High ~2.5 V, CAN Low ~2.5 V (differential ~0 V idle); look for ~2.5 V on both with key ON and no traffic; active differential pulses during communication
Expected data traffic: periodic CAN frames from rear radar module (bus traffic visible on scan tool or scope); common bus baud rates 250 kbps or 500 kbps depending on vehicle
No long-duration dominant states (stuck high/low) on CAN lines; no excessive noise or reflections on oscilloscope

Connect a capable scan tool and read all U-codes and related module data; record freeze-frame and occurrence conditions
Check for manufacturer service information, TSBs, and required software/firmware levels for radar systems
Visually inspect rear radar module C, connector and wiring for damage, corrosion, moisture, loose pins or foreign objects; repair as needed
Verify module power and ground at the radar connector with ignition in the required state; confirm battery voltage and good ground continuity
With ignition ON, use a multimeter or oscilloscope to check CAN High/Low voltages at the radar connector and elsewhere on the same bus; verify expected idle and active signals
If CAN voltages are abnormal, isolate by disconnecting other devices per wiring diagram and re-check to locate short or open
Check for intermittent faults by wiggle-testing the connector and harness while monitoring scan tool for changes
If wiring and power are good and bus traffic looks normal but invalid data persists, try updating module software or reprogramming per manufacturer procedure
If available, swap with a known-good radar module C (or known-good wiring harness) or connect module to a diagnostic bench to confirm behavior
After repair or module replacement, clear codes, perform required calibrations or sensor teach-in, then road-test and re-scan to verify the fault does not return

Connector/wiring fault to Rear Radar Module C (corrosion, bent pins, open/short)
Failed radar module hardware or internal electronics
CAN bus communication fault (open, short to battery/ground, high impedance)
Low supply voltage or bad ground at the module
Software/firmware mismatch or missing calibration after replacement