Invalid Data from Restraint Sensor I
Diagnostic trouble code U0479 indicates that a control module, typically the Restraint Control Module (RCM) or Airbag Control Module (ACM), has received invalid, out-of-range, or corrupted data from Restraint Sensor I over the CAN bus. Unlike a loss-of-communication code (U01xx), communication is present but the message content is faulty due to checksum or CRC errors.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Faulty Restraint Sensor I (impact sensor, occupant sensor, pretensioner, etc.) generating an erroneous signal
- Damaged wiring or connectors (short, open, high resistance) between the sensor and the module
- Electromagnetic interference (EMI) on the CAN bus
- Internal processing failure in the Restraint Control Module (RCM/ACM)
- Software or calibration mismatch between the sensor and receiving module
3. Symptoms You Will Notice
- Airbag warning light illuminated
- Possible disabling of supplemental restraint system (SRS)
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect wiring and connectors between Restraint Sensor I and the RCM/ACM for damage or corrosion
Test sensor resistance and signal output per manufacturer specifications
Check for EMI sources near the CAN bus wiring
If wiring and sensor are okay, attempt to reprogram or replace the RCM/ACM
5. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive. The airbags may not deploy correctly in a crash, increasing injury risk. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
Repair costs typically range from $150 to $1,200, depending on whether the sensor, wiring, or module needs replacement. Diagnostic fees are usually $100–$150.