U0499

Code

Generic U — Network/User

Invalid Data Received From Telematic Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 22 EN: 35 RU: 25

AI status

Completed

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Completed 100%

Page language: EN

Causes

Corrupted or malformed CAN/LIN message from the telematic control module
Software/calibration mismatch between TCM and other modules
TCM firmware bug or memory corruption
Faulty or intermittent wiring, connectors, or sockets on the telematics module or CAN bus
Faulty CAN transceiver or physical layer faults (shorts, high resistance, open circuit)
Low battery voltage, poor battery connections or weak ground affecting module operation

Symptoms

Stored U0499 DTC and possible related network codes
Loss or intermittent operation of telematics features (remote services, SOS, data transmission)
Malfunction indicator lamps or network warning messages on dash (may vary by manufacturer)
Other modules reporting communication errors or invalid data codes
No response or limited response from telematics module via diagnostic tool

What to check

Read all stored and pending DTCs from all modules; record freeze frame and occurrence counters
Check for related U-codes or module-specific codes that indicate the bus or specific node
Visually inspect TCM connector and harness for corrosion, bent pins, water intrusion or damage
Verify battery voltage and chassis/body/engine ground integrity
Confirm presence and health of CAN/LIN bus (no aftermarket taps, devices, or adapters)
Attempt to communicate with the TCM using a factory-level scan tool to read software/calibration IDs

Signal parameters

TCM CAN message ID(s) on vehicle network (manufacturer-specific, typically in the 0x7xx–0x7FF or 0x18xxxxxx ranges) — verify expected message ID is present
Message interval / frequency — verify periodic frame is present (example: every 100–1000 ms as specified)
Data payload expected ranges for key bytes (plausibility checks) — check for out-of-range or constant values
Checksum/CRC field (if used) — verify computed CRC matches message field
CAN bus electrical levels: dominant ~0V, recessive ~2.5V midpoint; measure differential swing with O-scope
Bus error counters and node transmit/receive error rates reported by diagnostic tool

Diagnostic algorithm

Retrieve and document U0499 plus all other stored network codes and freeze frame data from all modules.
Check for related codes that indicate which module reported the invalid data and whether multiple modules see the same problem.
Inspect TCM connector and harness for corrosion, water, damaged pins or poor retention; repair as necessary.
Verify battery voltage (12.6V nominal, >12V with key on) and inspect ground points for cleanliness and tightness.
With a scan tool, attempt to communicate directly with the TCM. Note software/calibration part numbers and compare to other modules for compatibility.
Monitor the vehicle network with a scan tool or CAN/LIN bus analyzer while exercising telematics functions to capture the invalid message and timestamps.
Use an oscilloscope to check physical layer signals on CAN_H/CAN_L for noise, missing recessive/dominant transitions, or bus reflections. Measure voltages and differential amplitude.
If the message is present but payload values are implausible, consider TCM software corruption—check for available reflash/updates and perform per manufacturer procedure.
If wiring or transceiver fault is suspected, isolate segments or disconnect aftermarket devices and re-test. Repair wiring or replace transceiver as needed.
If all network and power checks are OK and reflashing doesn’t resolve the issue, consider replacing the TCM with a correctly programmed unit and verify programming/calibration after replacement.
Clear codes and perform a road test and extended network monitoring to confirm the repair and that the code does not return.

Likely causes

Temporary software glitch in the TCM (requires reflash or reset)
Communication error on CAN bus due to wiring/connector fault
TCM not programmed/configured to vehicle (replacement or mismatch)
Faulty TCM hardware or corrupted firmware
Interference from aftermarket telematics or accessory module

Fault status

⚠️ Status

Network communication DTC stored. U0499 indicates the receiving module detected invalid or implausible data from the Telematic Control Module. Code may be stored as confirmed or pending depending on recurrence; related network or module codes often present. Freeze frame and occurrence counter may be available.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours

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