U0398

Code

Generic U — Network/User

Invalid Data Received From Vehicle Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 15 EN: 19 RU: 21

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Corrupted or malformed CAN/LIN/vehicle-bus message
Faulty or misconfigured control module (ECU/TCU/BCM/ABS/etc.)
Wiring harness damage, short, open, or intermittent connection on bus lines
Poor or missing ground or battery voltage fluctuations
Software mismatch, missing calibration, or failed module update
Bus termination or wiring topology issues (high impedance, reflections)

Symptoms

One or more U-codes stored in multiple modules
Malfunction indicators or warning messages (varies by vehicle)
Erratic instrument cluster displays or incorrect readings from other modules
Intermittent loss of communication with the affected module
Related system malfunctions depending on source module (e.g., transmission shifting, ABS messages)
No drivability symptoms if only data integrity is affected

What to check

Read all stored DTCs and freeze frame data from all modules; note occurrence frequency and correlated codes
Check latest software/calibration levels for modules and compare with manufacturer data
Verify battery voltage (engine off and cranking) and inspect main power/ground connections
Visually inspect wiring harnesses and connectors on suspected modules for corrosion, damage, or loose pins
Check for damaged CAN/LIN connectors, bent pins, or aftermarket devices tied to the bus
Use a scan tool to monitor live data and message frequencies while recreating the issue

Signal parameters

CAN ID / arbitration ID of suspect message
Data length code (DLC) and specific byte offsets
Message frequency (Hz) or period
Checksum or CRC fields and message counters
Bus voltage levels (dominant and recessive) and waveform integrity
Timestamp and sequence numbers (if used)

Diagnostic algorithm

Record all related codes and note which modules reported U0398 and any concurrent U or P codes.
Verify battery voltage and main grounds; repair loose or corroded connections and retest after voltage is stable.
Visually inspect and wiggle-test connectors and wiring for the modules that transmit or receive the invalid data; repair any faults.
Use a scan tool to observe live messages from the suspected source module(s); compare reported values to known-good ranges or a reference vehicle if available.
Use a CAN/LIN bus analyzer or oscilloscope to capture traffic while the fault occurs; check for malformed frames, incorrect DLC, bad checksums, abnormal bus voltage, or bus-off events.
If a specific module is identified as sending invalid frames, check for available software updates or reflash the module per manufacturer procedure; clear codes and retest.
Isolate the problem by disconnecting non-essential modules or aftermarket devices from the bus one at a time (with safe procedures) to see if the fault clears.
If wiring harness or connector damage is found, repair using approved splices/terminals; replace or repair the harness as necessary and verify repair.
If after wiring and software checks the module still transmits invalid data, consider replacing the suspect control module following proper programming and configuration steps.
After repair, clear codes and verify normal communication over an extended drive cycle; confirm no recurrence and that all related systems operate correctly.

Likely causes

Incorrect or corrupted message from a specific control module (software fault)
Damaged/loose connector or wiring to the module transmitting invalid data
CAN/LIN bus integrity problems (open/short, missing termination, high resistance)
Low battery voltage or poor ground causing data corruption

Fault status

⚠️ Status

Invalid data received from vehicle control module — a transmitted message failed validation or contained unexpected values, indicating communication or data integrity issues.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours