Code
U0479
Generic
U — Network/User
Invalid Data Received From Restraints System Sensor I
AI status
Completed
Completed
100%
Causes
- Faulty restraints system sensor (seat belt buckle, occupant sensor, side impact sensor, etc.)
- Intermittent or failed CAN/LIN network communication between sensor and RCM
- Damaged wiring or poor connector/crimp (open, short to ground, short to battery, high resistance)
- Low or unstable supply/ground to the sensor or RCM
- Faulty restraints control module (RCM) or other module sending/relaying messages
- Software/configuration mismatch or corrupted module calibration
Symptoms
- Airbag / SRS warning lamp ON
- Possible disablement of one or more restraint functions (e.g., seatbelt pretensioner or airbag)
- DTC(s) stored in restraint control module and possibly other modules
- Intermittent or permanent loss of occupant classification/seat belt buckle status
- No drivability symptoms in many cases (this is a safety system fault)
What to check
- Read and record all stored DTCs and freeze frame data with a capable scan tool
- Check for other network-related codes (U0100, U0121, etc.) that indicate bus problems
- Visually inspect sensor connectors and wiring for corrosion, damage, or poor seating
- Perform a wiggle test on wiring/connectors while monitoring live data/messages
- Verify battery voltage and ground integrity at the RCM and sensor
- Check CAN/LIN bus voltages and continuity according to vehicle service data
Signal parameters
- Typical CAN recessive voltage: both CAN_H and CAN_L ≈ 2.5 V (vehicle dependent)
- Typical CAN dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (differential ≈ 2.0 V)
- Expected message frequency from restraints sensors often between 5–100 Hz (model dependent)
- Supply/reference voltages: many SRS sensors use regulated 5 V or vehicle battery 12 V feed — check OEM spec
- Look for frequent CRC/frame errors, missing messages, or malformed payloads in the sensor’s CAN/LIN frames
Diagnostic algorithm
- Safety first: Follow the manufacturer's SRS safety procedure. Disable the battery power to the vehicle's SRS (remove negative terminal and wait manufacturer-specified time) before disconnecting SRS components.
- Use a factory-capable or equivalent scan tool. Read all codes and freeze-frame data from the restraints control module and other modules on the bus.
- Note whether U0479 is current or historic. Recreate the fault conditions if possible (seat occupancy, buckle/unbuckle, door cycle) while monitoring live data.
- Visually inspect the wiring and connector for the indicated restraints system sensor (pin damage, corrosion, bent pins, moisture). Repair or clean as required.
- With ignition ON (follow safety guidance), backprobe the sensor connector and verify supply voltage and ground reference against OEM specs. Check for unstable or missing supply.
- Check CAN/LIN bus integrity: measure CAN_H and CAN_L voltages with respect to chassis ground and verify proper recessive/dominant levels and termination resistance (approx. 60 Ω across CAN_H/L for many systems).
- Monitor the bus with a scan tool or oscilloscope for missing messages, CRC errors or malformed frames from the sensor node. A logic/oscilloscope trace can reveal noise or intermittent faults.
- If wiring and bus appear good, disconnect the suspect sensor and see if the code changes to a sensor open or different DTC. Reconnect and test again.
- If the sensor is confirmed faulty, replace the sensor and reconnect. If replaced, follow required calibration, programming, or initialization for the new sensor per OEM procedures.
- Clear codes, perform a functional test and test drive to confirm the code does not return. If code returns, escalate to module replacement or deeper network diagnosis per factory service information.
Likely causes
- Corroded/loose connector at the sensor or RCM
- Broken or pinched wiring harness on the sensor circuit
- Sensor internal failure
- Network data errors caused by a shorted CAN/LIN bus line or bad termination
Fault status
Status
Invalid data received from restraints system sensor I — communication or sensor data error detected.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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Code
U0479
HYUNDAI
U — Network/User
Invalid Data Received From “Restraints System Sensor I”
AI status
Completed
Completed
100%
Causes
- Faulty restraints system sensor (seat belt buckle, occupant sensor, side impact sensor, etc.)
- Intermittent or failed CAN/LIN network communication between sensor and RCM
- Damaged wiring or poor connector/crimp (open, short to ground, short to battery, high resistance)
- Low or unstable supply/ground to the sensor or RCM
- Faulty restraints control module (RCM) or other module sending/relaying messages
- Software/configuration mismatch or corrupted module calibration
Symptoms
- Airbag / SRS warning lamp ON
- Possible disablement of one or more restraint functions (e.g., seatbelt pretensioner or airbag)
- DTC(s) stored in restraint control module and possibly other modules
- Intermittent or permanent loss of occupant classification/seat belt buckle status
- No drivability symptoms in many cases (this is a safety system fault)
What to check
- Read and record all stored DTCs and freeze frame data with a capable scan tool
- Check for other network-related codes (U0100, U0121, etc.) that indicate bus problems
- Visually inspect sensor connectors and wiring for corrosion, damage, or poor seating
- Perform a wiggle test on wiring/connectors while monitoring live data/messages
- Verify battery voltage and ground integrity at the RCM and sensor
- Check CAN/LIN bus voltages and continuity according to vehicle service data
Signal parameters
- Typical CAN recessive voltage: both CAN_H and CAN_L ≈ 2.5 V (vehicle dependent)
- Typical CAN dominant state: CAN_H ~3.5 V, CAN_L ~1.5 V (differential ≈ 2.0 V)
- Expected message frequency from restraints sensors often between 5–100 Hz (model dependent)
- Supply/reference voltages: many SRS sensors use regulated 5 V or vehicle battery 12 V feed — check OEM spec
- Look for frequent CRC/frame errors, missing messages, or malformed payloads in the sensor’s CAN/LIN frames
Diagnostic algorithm
- Safety first: Follow the manufacturer's SRS safety procedure. Disable the battery power to the vehicle's SRS (remove negative terminal and wait manufacturer-specified time) before disconnecting SRS components.
- Use a factory-capable or equivalent scan tool. Read all codes and freeze-frame data from the restraints control module and other modules on the bus.
- Note whether U0479 is current or historic. Recreate the fault conditions if possible (seat occupancy, buckle/unbuckle, door cycle) while monitoring live data.
- Visually inspect the wiring and connector for the indicated restraints system sensor (pin damage, corrosion, bent pins, moisture). Repair or clean as required.
- With ignition ON (follow safety guidance), backprobe the sensor connector and verify supply voltage and ground reference against OEM specs. Check for unstable or missing supply.
- Check CAN/LIN bus integrity: measure CAN_H and CAN_L voltages with respect to chassis ground and verify proper recessive/dominant levels and termination resistance (approx. 60 Ω across CAN_H/L for many systems).
- Monitor the bus with a scan tool or oscilloscope for missing messages, CRC errors or malformed frames from the sensor node. A logic/oscilloscope trace can reveal noise or intermittent faults.
- If wiring and bus appear good, disconnect the suspect sensor and see if the code changes to a sensor open or different DTC. Reconnect and test again.
- If the sensor is confirmed faulty, replace the sensor and reconnect. If replaced, follow required calibration, programming, or initialization for the new sensor per OEM procedures.
- Clear codes, perform a functional test and test drive to confirm the code does not return. If code returns, escalate to module replacement or deeper network diagnosis per factory service information.
Likely causes
- Corroded/loose connector at the sensor or RCM
- Broken or pinched wiring harness on the sensor circuit
- Sensor internal failure
- Network data errors caused by a shorted CAN/LIN bus line or bad termination
Fault status
Status
Invalid data received from restraints system sensor I — communication or sensor data error detected.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
Manual library for HYUNDAI
371
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