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Home / DTC / U0173 — Lost Communication With Restraints System Sensor D

U0173 — Lost Communication With Restraints System Sensor D

Detailed page for trouble code U0173.

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Code

U0173

Generic U — Network/User

Lost Communication With Restraints System Sensor D

Brand: Generic
Type: U — Network/User
Views: UK: 14 EN: 20 RU: 16
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short or high resistance in CAN/communication wiring between sensor D and the network
  • Disconnected, corroded or damaged connector at the sensor or harness
  • Blown fuse or switched power supply to the restraints sensor/module
  • Failed restraints sensor/module (internal electronics fault)
  • Network termination or wiring fault (missing/incorrect termination, short CAN_H to CAN_L)
  • Low battery voltage or intermittent supply to the restraints network

Symptoms

  • SRS/Airbag warning lamp illuminated or flashing on instrument panel
  • Stored U0173 DTC (may be permanent until communication restored)
  • Related restraints system features disabled (seatbelt pre-tensioner, side airbag status)
  • Possible other U-codes for other modules on the same network
  • Vehicle may fail subsequent SRS self-tests or diagnostics

What to check

  • Use a scan tool to read U0173 freeze frame and related DTCs from all modules on the SRS/CAN network
  • Verify battery voltage is within specification (engine off and cranking conditions as required)
  • Check SRS and related fuses/relays for presence of power
  • Visually inspect connectors and harness routing to Restraints Sensor D for corrosion, damage or disconnection
  • Check for presence of the sensor/module on the CAN network (module list or node presence in scan tool)
  • Measure CAN bus voltages: CAN_H and CAN_L idle voltages and continuity to other nodes

Signal parameters

  • Module periodically transmits a restraints status message on the vehicle CAN bus (expected regular update rate — typically tens of ms to 1 s depending on OEM)
  • Expected idle voltages: CAN_H ~2.5–3.5 V, CAN_L ~1.5–1.0 V (verify with OEM spec)
  • Termination: ~60 ohms across CAN_H and CAN_L when bus intact
  • When healthy, the module should appear in module list / network node scan and provide status bytes (presence, sensor status, fault flags)
  • No or sporadic packets from sensor D indicates a communication/power or internal module fault

Diagnostic algorithm

  1. Connect a capable scan tool and record stored faults and freeze frame from all network modules. Note any other U-codes.
  2. Check battery voltage and SRS-related fuses/relays. Replace any blown fuses and retest communication.
  3. Inspect and reseat the physical connector at Restraints Sensor D (follow manufacturer safety procedures for SRS work). Look for bent pins, corrosion, or water intrusion.
  4. Verify the sensor/module is present on the CAN bus using the scan tool (module list or bus monitor). If absent, backprobe the sensor connector to verify power and ground at the module.
  5. Test CAN bus continuity: check resistance between CAN_H and CAN_L (termination), and continuity from the sensor connector to other known-good nodes or the ECU. Look for shorts to ground or battery.
  6. If supply or CAN wiring is suspect, trace and repair wiring harness damage. Perform wiggle tests while monitoring live data for intermittent faults.
  7. If wiring and power are good but no communication, attempt a known-good sensor/module (if available) or replace the sensor module. Program/configure per OEM instructions if required.
  8. After repair or replacement, clear codes and perform SRS system self-test. Verify no U0173 returns and that SRS warning lamp behavior is normal.
  9. If code persists and wiring and replacements are verified, consult OEM wiring diagrams, service bulletins, and consider module reflash or control module replacement as directed.

Likely causes

  • Sensor D connector unplugged after seat/service or collision
  • Chafed wiring in seat or door pillar harness (common flex points)
  • Corroded pins inside the sensor/module connector causing intermittent contact
  • Faulty sensor/module that does not transmit periodic status messages
  • Blown SRS-related fuse or relay disabling sensor power
  • CAN bus short to chassis or battery at the sensor harness

Fault status

⚠️ Status
Lost Communication With Restraints System Sensor D
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0164
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Code

U0173

HYUNDAI U — Network/User

Lost Communication With “Restraints System Sensor D”

Brand: HYUNDAI
Type: U — Network/User
Views: UK: 11 EN: 16 RU: 16
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short or high resistance in CAN/communication wiring between sensor D and the network
  • Disconnected, corroded or damaged connector at the sensor or harness
  • Blown fuse or switched power supply to the restraints sensor/module
  • Failed restraints sensor/module (internal electronics fault)
  • Network termination or wiring fault (missing/incorrect termination, short CAN_H to CAN_L)
  • Low battery voltage or intermittent supply to the restraints network

Symptoms

  • SRS/Airbag warning lamp illuminated or flashing on instrument panel
  • Stored U0173 DTC (may be permanent until communication restored)
  • Related restraints system features disabled (seatbelt pre-tensioner, side airbag status)
  • Possible other U-codes for other modules on the same network
  • Vehicle may fail subsequent SRS self-tests or diagnostics

What to check

  • Use a scan tool to read U0173 freeze frame and related DTCs from all modules on the SRS/CAN network
  • Verify battery voltage is within specification (engine off and cranking conditions as required)
  • Check SRS and related fuses/relays for presence of power
  • Visually inspect connectors and harness routing to Restraints Sensor D for corrosion, damage or disconnection
  • Check for presence of the sensor/module on the CAN network (module list or node presence in scan tool)
  • Measure CAN bus voltages: CAN_H and CAN_L idle voltages and continuity to other nodes

Signal parameters

  • Module periodically transmits a restraints status message on the vehicle CAN bus (expected regular update rate — typically tens of ms to 1 s depending on OEM)
  • Expected idle voltages: CAN_H ~2.5–3.5 V, CAN_L ~1.5–1.0 V (verify with OEM spec)
  • Termination: ~60 ohms across CAN_H and CAN_L when bus intact
  • When healthy, the module should appear in module list / network node scan and provide status bytes (presence, sensor status, fault flags)
  • No or sporadic packets from sensor D indicates a communication/power or internal module fault

Diagnostic algorithm

  1. Connect a capable scan tool and record stored faults and freeze frame from all network modules. Note any other U-codes.
  2. Check battery voltage and SRS-related fuses/relays. Replace any blown fuses and retest communication.
  3. Inspect and reseat the physical connector at Restraints Sensor D (follow manufacturer safety procedures for SRS work). Look for bent pins, corrosion, or water intrusion.
  4. Verify the sensor/module is present on the CAN bus using the scan tool (module list or bus monitor). If absent, backprobe the sensor connector to verify power and ground at the module.
  5. Test CAN bus continuity: check resistance between CAN_H and CAN_L (termination), and continuity from the sensor connector to other known-good nodes or the ECU. Look for shorts to ground or battery.
  6. If supply or CAN wiring is suspect, trace and repair wiring harness damage. Perform wiggle tests while monitoring live data for intermittent faults.
  7. If wiring and power are good but no communication, attempt a known-good sensor/module (if available) or replace the sensor module. Program/configure per OEM instructions if required.
  8. After repair or replacement, clear codes and perform SRS system self-test. Verify no U0173 returns and that SRS warning lamp behavior is normal.
  9. If code persists and wiring and replacements are verified, consult OEM wiring diagrams, service bulletins, and consider module reflash or control module replacement as directed.

Likely causes

  • Sensor D connector unplugged after seat/service or collision
  • Chafed wiring in seat or door pillar harness (common flex points)
  • Corroded pins inside the sensor/module connector causing intermittent contact
  • Faulty sensor/module that does not transmit periodic status messages
  • Blown SRS-related fuse or relay disabling sensor power
  • CAN bus short to chassis or battery at the sensor harness

Fault status

⚠️ Status
Lost Communication With Restraints System Sensor D
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

U0100 U0121 U0140 U0155 U0164
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