U017D — Lost Communication With “Restraints System Sensor N”

Causes

• Open or shorted data bus wiring (CAN/LIN) between sensor N and restraints control module
• Poor connector connection, corrosion, bent pins, or water intrusion at sensor or harness connectors
• No power or poor ground to sensor N
• Failed or intermittent sensor/module (sensor N)
• Faulty restraints control module or other module on the same bus causing network issues
• Faulty termination resistor or bus wiring shorted to battery/chassis

Symptoms

• SRS / Airbag warning lamp illuminated
• Possible disablement of some restraint features (airbag deployment logic altered)
• Stored communication-related DTCs in restraints module and possibly other modules
• Inability to communicate with or configure sensor N via scan tool
• Intermittent or permanent faults that persist after key cycles

What to check

• Use a diagnostic scan tool to confirm U017D and view freeze frame or related codes
• Visually inspect connectors and wiring at sensor N and restraints control module for damage/corrosion
• Verify sensor power and ground with key ON (refer to vehicle pinout for correct pins)
• Check for presence of CAN/LIN messages from sensor N using a capable scanner or scope
• Measure CAN bus termination resistance (approx. 60 ohms between CANH and CANL across the bus)
• Check for related fuses and modules on same bus; inspect for recent repairs or water damage

Signal parameters

• CAN bus idle: CANH and CANL near vehicle reference (≈2.5 V common-mode) each; dominant state produces differential ~1.5–3.0 V
• Expected differential amplitude on dominant bits: ~1.5–2.5 V (CANH higher than CANL)
• Typical bus termination: ≈60 ohms total between CANH and CANL (two 120 ohm terminators in parallel)
• Expected message frequency: restraints sensors commonly transmit cyclic or on-event messages — verify with OEM data (messages often every 10–100 ms or on event)
• Power supply: sensor Vbatt nominal ~12 V (verify exact pin and range from OEM documentation)

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