Code
U0494
Generic
U — Network/User
Invalid Data Received From Digital Audio Control Module A
Views:
UK: 14
EN: 26
RU: 24
AI status
Completed
Completed
100%
Causes
- Faulty Digital Audio Control Module A (hardware or software)
- Damaged, corroded, or loose connectors or wiring between the DACM and vehicle data bus
- CAN/LIN/MOST bus faults (short to battery/ground, open, high bus error rate)
- Improper termination or missing termination resistor
- Interference from aftermarket audio or other devices on the network
- Incorrect or incompatible software calibration or module programming
Symptoms
- Audio system malfunctions (no sound, intermittent audio, wrong source selection)
- Warning message or message center alert about audio module communication
- Other modules show related network communication codes or degraded features
- Intermittent operation of steering-wheel audio controls or display info
- Unusual behavior of infotainment (frozen screen, random resets)
What to check
- Read all stored codes and freeze-frame data from all modules; note related U-codes and time stamps
- Check vehicle battery voltage and charging system; ensure stable supply during diagnosis
- Visually inspect DACM connectors and wiring for damage, corrosion, or poor routing
- Check for aftermarket audio equipment or adapters and disconnect for test
- Use scan tool to verify the DACM is present on the bus and to monitor live network messages
- Check for CAN/LIN/MOST bus error counters and node presence with a capable scan tool or oscilloscope
Signal parameters
- CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V
- CAN bus dominant: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
- Typical CAN termination: approx. 60 ohms across CAN_H and CAN_L (two 120 Ω resistors in parallel)
- Common CAN data rates: 500 kb/s or 250 kb/s (verify vehicle-specific baud rate)
- Message integrity: valid message IDs, correct DLC, proper CRC/checksum and expected periodic intervals
- LIN (if used): single-wire low-speed topology; typical wake and data voltage referenced to battery
Diagnostic algorithm
- Verify and record all DTCs from every control module. Note whether U0494 is current or historic and whether other U-codes are present.
- Confirm stable battery voltage (12.6 V resting, >11 V cranking/discovery tests). Recharge or connect a stable power supply if required during testing.
- Inspect DACM connectors, mating harness, grounds and power feed for corrosion, bent pins, or loose connections. Repair as needed.
- With a scan tool, check that the DACM is present/responding on the network. View live data/messages from the DACM (if available) and verify the content looks reasonable.
- Monitor the vehicle network with an oscilloscope or a capable diagnostic tool while reproducing the fault. Look for excessive bit errors, bus voltage abnormalities, spikes, or missing frames from the DACM.
- Measure termination resistance across CAN_H and CAN_L at multiple points; repair open or incorrect termination.
- If aftermarket components are installed, disconnect them and retest. Remove non-factory modules that share the same bus temporarily.
- Perform wiggle/stress tests on harnesses and connectors while monitoring for message corruption or code appearance. Repair wiring harness faults found.
- If wiring and bus are good, check DACM power and ground circuits for proper voltage and continuity. Replace or repair as needed.
- Verify module software/calibration level against factory specification. Reflash/update module software or reprogram replacement module per manufacturer procedure.
- Clear codes and perform road or bench test to attempt to reproduce the failure. If U0494 returns after wiring and software confirmed good, consider module replacement.
- After repair, re-scan all modules and ensure no related network codes remain and retained DTCs are cleared.
Likely causes
- DACM A producing corrupted or out-of-spec messages due to internal failure
- Connector pin corrosion or intermittent contact at the DACM or gateway
- Shorted or high-resistance CAN/LIN/MOST wires causing distorted signal levels
- Loss of proper bus termination (open/missing 120 ohm resistor)
- Aftermarket amplifier, head unit, or adapter injecting invalid messages
- Module software mismatch after update or replacement
Fault status
Status
Invalid data received from Digital Audio Control Module A — communication or data integrity fault detected.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
U0494
HYUNDAI
U — Network/User
Invalid Data Received From “Digital Audio Control Module A”
Views:
UK: 8
EN: 16
RU: 10
AI status
Completed
Completed
100%
Causes
- Faulty Digital Audio Control Module A (hardware or software)
- Damaged, corroded, or loose connectors or wiring between the DACM and vehicle data bus
- CAN/LIN/MOST bus faults (short to battery/ground, open, high bus error rate)
- Improper termination or missing termination resistor
- Interference from aftermarket audio or other devices on the network
- Incorrect or incompatible software calibration or module programming
Symptoms
- Audio system malfunctions (no sound, intermittent audio, wrong source selection)
- Warning message or message center alert about audio module communication
- Other modules show related network communication codes or degraded features
- Intermittent operation of steering-wheel audio controls or display info
- Unusual behavior of infotainment (frozen screen, random resets)
What to check
- Read all stored codes and freeze-frame data from all modules; note related U-codes and time stamps
- Check vehicle battery voltage and charging system; ensure stable supply during diagnosis
- Visually inspect DACM connectors and wiring for damage, corrosion, or poor routing
- Check for aftermarket audio equipment or adapters and disconnect for test
- Use scan tool to verify the DACM is present on the bus and to monitor live network messages
- Check for CAN/LIN/MOST bus error counters and node presence with a capable scan tool or oscilloscope
Signal parameters
- CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V
- CAN bus dominant: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
- Typical CAN termination: approx. 60 ohms across CAN_H and CAN_L (two 120 Ω resistors in parallel)
- Common CAN data rates: 500 kb/s or 250 kb/s (verify vehicle-specific baud rate)
- Message integrity: valid message IDs, correct DLC, proper CRC/checksum and expected periodic intervals
- LIN (if used): single-wire low-speed topology; typical wake and data voltage referenced to battery
Diagnostic algorithm
- Verify and record all DTCs from every control module. Note whether U0494 is current or historic and whether other U-codes are present.
- Confirm stable battery voltage (12.6 V resting, >11 V cranking/discovery tests). Recharge or connect a stable power supply if required during testing.
- Inspect DACM connectors, mating harness, grounds and power feed for corrosion, bent pins, or loose connections. Repair as needed.
- With a scan tool, check that the DACM is present/responding on the network. View live data/messages from the DACM (if available) and verify the content looks reasonable.
- Monitor the vehicle network with an oscilloscope or a capable diagnostic tool while reproducing the fault. Look for excessive bit errors, bus voltage abnormalities, spikes, or missing frames from the DACM.
- Measure termination resistance across CAN_H and CAN_L at multiple points; repair open or incorrect termination.
- If aftermarket components are installed, disconnect them and retest. Remove non-factory modules that share the same bus temporarily.
- Perform wiggle/stress tests on harnesses and connectors while monitoring for message corruption or code appearance. Repair wiring harness faults found.
- If wiring and bus are good, check DACM power and ground circuits for proper voltage and continuity. Replace or repair as needed.
- Verify module software/calibration level against factory specification. Reflash/update module software or reprogram replacement module per manufacturer procedure.
- Clear codes and perform road or bench test to attempt to reproduce the failure. If U0494 returns after wiring and software confirmed good, consider module replacement.
- After repair, re-scan all modules and ensure no related network codes remain and retained DTCs are cleared.
Likely causes
- DACM A producing corrupted or out-of-spec messages due to internal failure
- Connector pin corrosion or intermittent contact at the DACM or gateway
- Shorted or high-resistance CAN/LIN/MOST wires causing distorted signal levels
- Loss of proper bus termination (open/missing 120 ohm resistor)
- Aftermarket amplifier, head unit, or adapter injecting invalid messages
- Module software mismatch after update or replacement
Fault status
Status
Invalid data received from Digital Audio Control Module A — communication or data integrity fault detected.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
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👎 Dislike
0
Send to email