Code
U0175
Generic
U — Network/User
Lost Communication With Restraints System Sensor F
Views:
UK: 17
EN: 22
RU: 22
AI status
Completed
Completed
100%
Causes
- Faulty or disconnected Restraints System Sensor F
- Damaged wiring harness or corroded connector at the sensor (open, short to ground/Vb, high resistance)
- Faulty module or ECU that communicates with the sensor
- CAN/LIN bus fault (open, short, missing termination, high noise)
- Blown fuse or loss of power/ground to the sensor or network node
- Intermittent connection due to water intrusion or pin damage
Symptoms
- SRS/airbag or restraints warning lamp illuminated
- Possible disabled airbag/pretensioner functions or reduced restraint capability
- Related diagnostic trouble codes stored in restraints or gateway modules
- Some vehicle functions tied to occupant sensing may be unavailable or behave incorrectly
What to check
- Use a capable scan tool to read current and stored U and B codes from gateway, restraint control module (RCM/SRS), and related modules
- Verify ignition on — check whether the sensor appears on the network (module list/messages)
- Visually inspect the sensor, connector, and wiring for damage, corrosion, or loose pins
- Check power and ground at the sensor connector (reference vehicle wiring diagram)
- Perform a wiggle test of harness while monitoring live data for intermittent loss
- Measure bus voltages and continuity for CAN/LIN lines; check termination resistors (~60 ohm CAN pair)
Signal parameters
- Typical network: CAN bus (high-speed) — differential CAN_H/CAN_L pair; idle approx. 2.5 V each, dominant state creates differential voltage (refer to OEM spec)
- Expected message presence: sensor/module publishes a periodic CAN message (frequency varies by vehicle — commonly 5–50 Hz)
- Message ID: manufacturer-specific (use OEM wiring/diagnostic data to identify Sensor F message ID)
- Bus termination: ~60 ohm total across CAN_H and CAN_L (two 120 ohm resistors in parallel)
- Acceptable resistance to ground on sensor signal circuits: near open on a good signal line (no direct short to ground or battery)
Diagnostic algorithm
- Safety first — follow manufacturer SRS safety procedures before inspecting or repairing; disable battery and wait required time when servicing SRS components
- Connect a professional scan tool and capture live network traffic; note whether the Restraints Sensor F node is present and whether it transmits messages
- Record freeze frame and related DTCs from SRS and gateway modules
- Inspect the sensor connector and wiring harness for corrosion, damage, bent pins, or water intrusion; repair or replace as required
- With ignition on, verify sensor supply power and ground at the connector using a DVOM (compare to wiring diagram). If power/ground absent, trace upstream — check fuses, relays, and connectors
- Check CAN/LIN bus: measure CAN_H and CAN_L voltage with key on and engine off; look for proper idle voltages and for short to battery/ground
- Perform continuity/resistance checks between the sensor connector and the control module connector to confirm no open or high resistance
- If wiring and power are good, swap in a known-good sensor (if available) or substitute a known-good module to confirm fault isolation
- If an ECU/module is suspected, consult OEM procedures for module programming, reflash, or replacement — do not replace modules without validating wiring and sensor function
- Clear codes and road-test to verify repair; monitor for reappearance of U0175 and related faults
Likely causes
- Disconnected or corroded connector at the sensor
- Wiring open/short between sensor and restraints module or gateway
- Faulty sensor or its internal electronics
Fault status
Status
Lost Communication With Restraints System Sensor F — controller reports timeout/no response from the sensor node on the vehicle data bus. May be stored as intermittent or continuous; freeze frame and related SRS codes may be present.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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