U0175

Code

Generic U — Network/User

Lost Communication With Restraints System Sensor F

Brand: Generic

Type: U — Network/User

Views: UK: 24 EN: 35 RU: 26

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Page language: EN

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