U0179

Code

HYUNDAI U — Network/User

Lost Communication With “Restraints System Sensor J”

Brand: HYUNDAI

Type: U — Network/User

Views: UK: 10 EN: 17 RU: 8

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in CAN high/low wiring to Restraints System Sensor J
Corroded, pushed-out or damaged connector at the sensor or SRS control module
Failed Restraints System Sensor J (internal electronics)
Faulty SRS control module or other gateway/module that relays messages
Missing or incorrect CAN bus termination (open or extra resistance)
Low battery voltage or intermittent power/ground to sensor or SRS module

Symptoms

Airbag / SRS warning lamp illuminated on instrument panel
Possible disabling of one or more airbag/pretensioner functions
SRS diagnostic trouble code stored (U0179 plus maybe related SRS codes)
Some vehicle systems that rely on restraint sensor data may be limited or show faults
No obvious drivability symptoms if only an SRS sensor node is affected

What to check

Read all stored codes and freeze-frame data with a capable scan tool; record related U- and B- codes
Visual inspection of wiring and connectors for Restraints System Sensor J and harness routing
Check vehicle battery voltage and charging system; ensure stable 12V supply
Inspect/clean pins and terminals at sensor connector and SRS control module
Check for aftermarket devices or recent repairs that tapped the CAN bus
Confirm proper CAN termination resistance (~60 ohms across CAN H/L with ignition off)

Signal parameters

CAN bus idle (recessive): CANH ≈ 2.5 V, CANL ≈ 2.5 V (both equal)
CAN bus dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2.0 V)
Typical bus speeds for in-vehicle CAN networks: commonly 250 kb/s or 500 kb/s (verify in service manual)
Normal termination: ~60 ohms between CANH and CANL (two 120 ohm resistors in parallel)

Diagnostic algorithm

Safety first — follow manufacturer SRS safety procedures. Disable battery power as specified and wait required time before disconnecting SRS connectors.
Scan: Connect a scan tool, read U0179 plus any related codes and note freeze-frame / occurrence count.
Visual: Inspect sensor J connector, pins, and harness for damage, corrosion, or water intrusion; repair any visible faults.
Power/Ground: Verify sensor power and ground circuits with wiring diagrams. Check for proper voltage at the sensor connector with ignition on (per service manual).
Bus check: With ignition on, measure CANH/CANL at the sensor connector. Compare voltages to expected idle and dominant values. Wiggle harness to look for intermittent changes.
Termination: Measure resistance between CANH and CANL (ignition off). Confirm ~60 ohms. If open or very high/low, trace termination/shorts.
Continuity: With connector disconnected, perform pin-to-pin continuity from sensor connector to the SRS control module and to nearest splice points; repair breaks.
Module/Node isolation: If wiring checks good, substitute a known-good sensor or connector (if available) or connect an equivalent CAN node to verify bus behavior; do not attempt to power an airbag module outside approved procedures.
Intermittent or multiple module faults: Inspect entire CAN segment for shorts to battery/ground and for aftermarket devices. Repair as needed.
Clear codes: After repairs, clear codes and perform full system scan and SRS self-test. Verify code does not return and SRS lamp extinguishes.
If fault persists: follow OEM flowchart—consider replacing the affected restraints sensor module or SRS control module only after wiring and bus integrity are confirmed.

Likely causes

Damaged wiring harness or chafed insulation on the SRS sensor circuit near the sensor or under seats
Connector corrosion or bent pins at the sensor or SRS module
Sensor module internal failure (no wake/response on bus)
CAN bus short to battery or ground caused by accident damage or previous repairs
Loss of module power/ground (fused circuit open or poor ground)

Fault status

⚠️ Status

Lost communication with Restraints System Sensor J — the sensor node is not responding on the CAN bus. SRS fault stored and airbag warning lamp is/should be illuminated. Resolve wiring, power/ground, or module fault before returning vehicle to service.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email

U0179 — Lost Communication With “Restraints System Sensor J”