U017A

Code

HYUNDAI U — Network/User

Lost Communication With “Restraints System Sensor K”

Brand: HYUNDAI

Type: U — Network/User

Views: UK: 16 EN: 17 RU: 11

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in wiring between sensor K and restraints control module/CAN bus
Corroded or loose connector at the sensor or SRS control module
Faulty Restraints System Sensor K (internal electronics failure)
Power or ground fault to the sensor (blown fuse, poor ground)
CAN bus short to battery or ground, missing termination, or bus-off condition
Software/firmware mismatch or module programming issue

Symptoms

SRS/airbag warning light illuminated or flashing
Stored U017A with possible additional U0xxx or B0xxx network codes
Seatbelt pretensioner or airbag functions disabled or inhibited
Certain restraint system functions not listed or incorrect in live data
Possible reduced vehicle safety system functionality

What to check

Scan for U017A and related U0xxx/B0xxx codes; record freeze-frame and history
Verify presence of Restraints System Sensor K in module list with factory scan tool (module detect/ping)
Perform visual inspection of sensor K connector, harness, and seat/seatback routing for damage or corrosion
Check fuses and SRS power/ground circuits for the sensor
With safety procedures in place, measure sensor power and ground voltages at connector (battery voltage on power, low resistance to chassis ground)
Measure CAN bus voltages at sensor connector: idle both CAN_H and CAN_L ≈2.5V; during traffic CAN_H ~3.5V and CAN_L ~1.5V (use scope if possible)

Signal parameters

CAN message presence/ID for Restraints Sensor K (message frequency — expect regular periodic frames from sensor)
CAN_H idle ≈2.5V, CAN_L idle ≈2.5V; dominant state CAN_H ≈3.5V, CAN_L ≈1.5V
Termination resistance ≈60 ohms between CAN_H and CAN_L
Sensor supply voltage ≈12V (or vehicle nominal battery voltage) and stable ground (
Message timeout threshold: module flags loss when expected frames not received within specified milliseconds (manufacturer dependent)

Diagnostic algorithm

Use a capable scan tool to verify U017A, capture freeze-frame, and check for other network/controller codes.
Follow Hyundai SRS safety procedures before performing any work on the airbag system (disable SRS as instructed by the manufacturer or use diagnostic tool functions).
Visually inspect the sensor connector, pins and harness along the seat/seatback for damage, corrosion, or disconnection.
Check fuse(s) and measure sensor power and ground at the connector; repair poor power/ground before proceeding.
With proper safety measures, check CAN_H and CAN_L at the sensor connector: verify idle voltages and look for activity. Use an oscilloscope to confirm the sensor’s message appears on the bus.
If CAN bus voltages are abnormal, trace wiring for short to battery/ground or open. Check termination resistors and inspect for other modules causing bus contention.
If bus and power are good but the sensor does not transmit, unplug the sensor and measure continuity to the control module; if wiring is OK, replace sensor K and re-test.
After repair or replacement, clear codes, perform manufacturer-specific SRS readiness checks, and confirm no new communication errors and that SRS lamp behavior returns to normal.
If replacement does not clear the condition, consider SRS control module fault or need for programming/calibration at dealer level; consult factory service information.

Likely causes

Connector corrosion or bent pins at sensor K
Damaged CAN H/CAN L pair near seat or sensor location
Failed sensor module (internal failure)
Blown SRS-related fuse or poor sensor ground
Other module on same CAN segment pulling the bus off (short)

Fault status

⚠️ Status

Lost Communication With “Restraints System Sensor K” — no or irregular CAN messages received from the specified restraints sensor, preventing normal restraints system communication.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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U017A — Lost Communication With “Restraints System Sensor K”