Fault Code Description
The U0123 fault code means that one or more vehicle control modules cannot communicate with the Yaw Rate Sensor Module. The lost communication occurs through the CAN Bus network, which is responsible for exchanging data between electronic control units.
The Yaw Rate Sensor provides critical information used by ESC, ABS, and traction control systems to determine whether the vehicle is stable or experiencing loss of control. If the module becomes unavailable, the vehicle may disable stability assistance features and illuminate warning indicators on the instrument cluster.
U0123 does not always indicate a failed sensor. The problem may be caused by a damaged CAN High or CAN Low circuit, weak battery voltage, poor grounding, connector corrosion, blown fuses, or an internal Yaw Rate Sensor Module failure.
Yaw Rate Sensor Network Overview
During normal operation, the Yaw Rate Sensor continuously communicates vehicle movement data to the stability control system. Any interruption in this communication path can trigger the U0123 code and disable safety-related functions.
Symptoms of U0123 Code
The symptoms caused by U0123 depend on the vehicle design and how the Yaw Rate Sensor Module is integrated into the stability control system. Since the sensor provides critical information for ESC and ABS operation, communication loss can disable several safety features.
| Symptom | Severity |
|---|---|
| ABS Warning Light | ★★★★★ |
| Electronic Stability Control (ESC) Warning | ★★★★★ |
| Traction Control Disabled | ★★★★★ |
| Multiple U-Series Communication Codes | ★★★★☆ |
| Vehicle Stability System Reduced | ★★★★☆ |
| Steering Stability Warning | ★★★★☆ |
Common Causes of U0123
U0123 is usually caused by a communication interruption between the Yaw Rate Sensor Module and the vehicle CAN network. The sensor itself is only one possible cause.
- Open circuit in CAN High wiring.
- Open circuit in CAN Low wiring.
- Short circuit between CAN wires.
- CAN Bus short to ground or battery voltage.
- Corroded or damaged Yaw Rate Sensor connector.
- Loss of battery power supply to the sensor module.
- Poor ground connection.
- Low battery voltage during starting.
- Damaged wiring harness after repairs or accidents.
- Internal failure of the Yaw Rate Sensor Module.
- Faulty ABS/ESC module communication gateway.
How Serious Is U0123?
The U0123 code is considered a high-priority safety-related fault because the Yaw Rate Sensor is essential for electronic stability systems. The vehicle may still drive normally, but important safety functions may not operate correctly during emergency maneuvers.
✔ ESC system may be disabled.
✔ Traction control may stop working.
✔ ABS-related functions may be affected.
✔ Diagnosis should be completed as soon as possible.
Estimated Repair Cost
The repair cost for U0123 depends on whether the problem is caused by wiring, connectors, power supply, or replacement of the Yaw Rate Sensor Module.
| Repair | Estimated Cost (USD) |
|---|---|
| Diagnostic Testing | $100–200 |
| CAN Wiring Repair | $100–450 |
| Connector Repair | $50–200 |
| Yaw Rate Sensor Calibration | $100–300 |
| Yaw Rate Sensor Replacement | $300–1,000+ |
| ABS/ESC Module Programming | $150–500 |
Diagnostic Procedure for U0123 Code
Diagnosing U0123 requires checking the complete communication path between the Yaw Rate Sensor Module and the vehicle CAN network. Before replacing any module, verify power supply, ground circuits, CAN Bus integrity, and connector condition.
↓ Scan All Control Modules
↓ Record Freeze Frame Data
↓ Check Battery Voltage
↓ Inspect Yaw Rate Sensor Fuse & Power Supply
↓ Verify Ground Circuit
↓ Measure CAN High / CAN Low
↓ Inspect Connectors & Wiring
↓ Check Live Data Communication
↓ Analyze Oscilloscope Waveform
↓ Repair Fault
↓ Clear DTC & Road Test
Electrical Inspection
The Yaw Rate Sensor Module requires stable power, ground, and CAN communication to operate correctly. Electrical testing should be performed before condemning the sensor or replacing expensive ABS-related components.
| Test | Normal Value |
|---|---|
| Battery Voltage | 12.4–12.8 V |
| Ignition Supply | Battery Voltage With Key ON |
| Ground Voltage Drop | Below 0.2 V |
| CAN Bus Resistance | Approximately 60 Ω |
| CAN High Signal | Approximately 2.5–3.5 V |
| CAN Low Signal | Approximately 1.5–2.5 V |
Live Data Analysis
A professional scan tool can confirm whether the Yaw Rate Sensor Module is online and communicating with the ABS and stability control systems.
| Parameter | Normal Condition | Fault Condition |
|---|---|---|
| Yaw Rate Sensor Status | Online | No Communication |
| Yaw Rate Value | Changes With Vehicle Movement | Missing / Frozen |
| CAN Network Status | Active | Communication Error |
| ESC System Status | Available | Disabled |
| Steering Angle Data | Normal Communication | Unavailable |
Professional Diagnostic Tips
- Check all stored communication codes before diagnosing U0123 alone.
- Do not replace the Yaw Rate Sensor before testing CAN Bus communication.
- Inspect the sensor location after water leaks or interior damage.
- Perform a zero-point calibration after sensor replacement when required.
- Use voltage-drop testing instead of relying only on continuity checks.
- Monitor Live Data while performing a harness wiggle test.
- Check ABS module communication because it is often the gateway for stability systems.
- Use an oscilloscope for intermittent CAN Bus faults.
Typical Wiring Diagram
The Yaw Rate Sensor Module depends on a stable power supply, ground connection, and CAN Bus communication line. The exact wiring configuration and connector pin locations vary by manufacturer, but most systems follow a similar network design.
Typical Yaw Rate Sensor Module Pinout
The following pinout is a general example. Always confirm the exact wiring diagram for the specific vehicle before testing.
| Pin | Circuit | Expected Reading |
|---|---|---|
| 1 | Battery Voltage Supply | 12V Battery Voltage |
| 2 | Ground Circuit | Below 0.2 Ω |
| 3 | CAN High | Approximately 2.5–3.5 V |
| 4 | CAN Low | Approximately 1.5–2.5 V |
| 5 | Calibration / Signal Circuit | Manufacturer Specific |
CAN Communication Signal Flow
The Yaw Rate Sensor does not directly control braking force. Instead, it sends vehicle movement information to the ABS/ESC module, which compares the data with wheel speed and steering angle information to determine if stability correction is required.
Connector Inspection Checklist
- Inspect the Yaw Rate Sensor connector for corrosion or moisture.
- Check terminals for looseness, spreading, or poor contact.
- Inspect wiring near the sensor mounting area for damage.
- Check for water intrusion inside the vehicle cabin.
- Verify power and ground circuits under load.
- Perform a CAN Bus network test before replacing the module.
- Check sensor mounting position because incorrect installation can affect calibration.
Recommended Diagnostic Tools
| Tool | Purpose |
|---|---|
| Professional Scan Tool | Read ABS, ESC, and communication codes |
| Digital Multimeter | Check power, ground, and resistance |
| Dual-Channel Oscilloscope | Analyze CAN High and CAN Low signals |
| Back Probe Leads | Safe connector testing |
Oscilloscope Waveform Analysis
Testing the CAN Bus waveform with a dual-channel automotive oscilloscope is one of the most accurate methods to diagnose U0123 Lost Communication With Yaw Rate Sensor Module. Oscilloscope testing can identify communication faults that may not appear during basic resistance or voltage checks.
Connect:
Channel A → CAN High
Channel B → CAN Low
Test at the Yaw Rate Sensor Module connector or the nearest CAN network access point.
Normal CAN Bus Waveform
CAN Low 2.5V ──╮───╮ ╭───╮ ╭── 1.5V ──╯ ╰────╯ ╰────╯
Result: Normal CAN communication. CAN High and CAN Low operate as complementary signals with correct voltage separation.
CAN High Open Circuit
CAN Low 2.5V ─╮─╮─╮─╮─╮─╮─╮─ 1.5V ─╯ ╰─╯ ╰─╯ ╰─╯ ╰
Possible Causes:
- Broken CAN High wire.
- Damaged terminal connection.
- Open circuit near sensor harness.
CAN Low Open Circuit
CAN Low 2.5V ────────────────────────
Possible Causes:
- Open CAN Low circuit.
- Loose connector pin.
- High resistance in wiring.
CAN Bus Short To Ground
CAN Low 0V ──────────────────────────
Diagnosis: Communication stops because CAN signals cannot change voltage levels correctly.
CAN Bus Short To Battery Voltage
CAN Low 5V ──────────────────────────
Diagnosis: CAN wiring may be contacting a power supply circuit.
Intermittent CAN Communication Fault
CAN Low ╰╯╰────╯ ╰╯╰────╯
Possible Causes:
- Loose connector terminals.
- Vibration damage in wiring.
- Water contamination.
- Poor ground connection.
- Intermittent sensor power supply.
Professional Oscilloscope Testing Tips
- Always capture CAN High and CAN Low together using two channels.
- Perform testing with ignition ON and during vehicle movement if possible.
- Use a trigger function to capture intermittent communication loss.
- Compare the waveform before and after repair.
- A missing waveform does not always mean a failed sensor; verify module power first.
- Use the oscilloscope together with Live Data for accurate diagnosis.
OBD Spark Diagnostic Reference
For more automotive communication fault guides, CAN Bus analysis, and professional diagnostic information, visit OBD Spark.
Recommended Repairs for U0123
After confirming the cause of U0123 Lost Communication With Yaw Rate Sensor Module, the repair should focus on restoring communication between the sensor module and the CAN network. Replacing the Yaw Rate Sensor should only be considered after verifying power, ground, wiring, and communication circuits.
| Repair | Estimated Cost |
|---|---|
| Repair CAN High / CAN Low Wiring | $100–450 |
| Repair Damaged Connector Terminals | $50–250 |
| Restore Sensor Power or Ground | $50–200 |
| Yaw Rate Sensor Calibration | $100–300 |
| Replace Yaw Rate Sensor Module | $300–1,000+ |
| ABS/ESC Module Programming | $150–500 |
Common Repair Mistakes
- Replacing the Yaw Rate Sensor without testing CAN Bus communication.
- Ignoring low battery voltage as a possible cause.
- Replacing the ABS module before checking sensor wiring.
- Using only a continuity test instead of voltage-drop testing.
- Failing to inspect connectors for corrosion or moisture.
- Skipping calibration after replacing the sensor.
- Clearing U0123 without recording Freeze Frame data.
- Ignoring additional U-series communication codes stored in other modules.
Manufacturer-Specific Repair Notes
The location and design of the Yaw Rate Sensor Module vary by manufacturer. Many vehicles install the sensor near the vehicle center of gravity, usually under the center console, beneath the seats, or near the transmission tunnel.
| Manufacturer | Common Diagnostic Notes |
|---|---|
| Toyota / Lexus | Check VSC, ABS communication and zero-point calibration |
| Honda / Acura | Inspect VSA system communication and sensor calibration |
| BMW | Check DSC module communication and CAN network |
| Mercedes-Benz | Check ESP system and steering angle synchronization |
| Ford | Inspect ABS module network communication |
| Hyundai / Kia | Check ESC module and CAN wiring |
Final Repair Verification
- Clear all stored DTCs after completing repairs.
- Confirm communication with the Yaw Rate Sensor Module.
- Verify ABS, ESC, and traction control systems are operational.
- Perform steering angle and yaw sensor calibration if required.
- Complete a road test under different driving conditions.
- Rescan the vehicle and confirm U0123 does not return.
Vehicle Applications
The U0123 code can appear in many vehicles equipped with Electronic Stability Control (ESC), Vehicle Stability Assist (VSA), or advanced ABS systems. Although the fault description remains the same, the location of the Yaw Rate Sensor Module and communication design can vary between manufacturers.
| Manufacturer | System Name | Common Inspection Area |
|---|---|---|
| Toyota / Lexus | VSC / ABS System | Yaw Sensor Calibration & CAN Communication |
| Honda / Acura | VSA Stability System | VSA Module Communication |
| BMW | DSC Stability Control | DSC Module & CAN Network |
| Mercedes-Benz | ESP System | ESP Communication & Calibration |
| Ford | AdvanceTrac | ABS Module Network |
| Hyundai / Kia | ESC System | ESC Module & Sensor Wiring |
| Volkswagen / Audi | ESP System | ABS Gateway Communication |
Professional Technician Tips
- Scan ABS, ESC, and body modules, not only the engine computer.
- Check battery condition before diagnosing communication faults.
- Inspect the Yaw Rate Sensor mounting area for water damage.
- Verify CAN Bus resistance before replacing the module.
- Use Live Data to confirm sensor communication status.
- Perform calibration procedures after sensor replacement.
- Check steering angle sensor data because it works together with yaw information.
- Confirm repairs with a complete road test.
Diagnostic Information Reference
For more detailed OBD-II communication diagnostics, CAN Bus testing procedures, and professional fault code guides, visit OBD Spark.
Frequently Asked Questions (FAQ)
What does the U0123 code mean?
The U0123 code means the vehicle has lost communication with the Yaw Rate Sensor Module through the CAN Bus network. The fault prevents stability control modules from receiving important vehicle movement information.
Can I drive with U0123?
The vehicle may continue driving, but safety systems such as Electronic Stability Control, traction control, and ABS assistance may be reduced or disabled. Driving should be limited until the problem is diagnosed.
Can a weak battery cause U0123?
Yes. Low battery voltage during starting or unstable charging system operation can interrupt communication between electronic modules and trigger U0123.
Is U0123 caused by a bad Yaw Rate Sensor?
Not always. Many U0123 faults are caused by wiring problems, damaged connectors, poor grounds, or CAN Bus communication issues. The sensor should only be replaced after proper testing.
Where is the Yaw Rate Sensor located?
The location depends on the manufacturer. It is commonly installed near the vehicle center of gravity, under the center console, beneath the seats, or near the transmission tunnel.
How do I diagnose U0123?
Diagnosis starts with scanning all control modules, checking battery voltage, inspecting power and ground circuits, testing CAN High and CAN Low communication, and verifying sensor Live Data.
What resistance should CAN Bus have?
With the ignition OFF and the battery disconnected, CAN High to CAN Low resistance is normally around 60 ohms on a properly terminated network.
Does replacing the Yaw Rate Sensor require programming?
Many vehicles require calibration or initialization after replacing the sensor. Some systems also require steering angle calibration and ABS/ESC module procedures.
Can a scan tool fix U0123?
A scan tool can clear codes and perform calibration procedures, but it cannot repair damaged wiring, failed power supplies, or physical communication problems.
Conclusion
The U0123 Code – Lost Communication With Yaw Rate Sensor Module is an important safety-related communication fault that affects stability control systems. A correct diagnosis requires checking the complete communication path, including power supply, ground circuits, CAN Bus wiring, connectors, and module operation.
Avoid replacing expensive ABS or stability components without testing the network first. In many cases, the repair involves correcting a wiring fault, repairing a connector, restoring power or ground, or performing the required calibration procedure.
For more professional OBD-II diagnostic guides, CAN Bus troubleshooting information, and automotive repair references, visit OBD Spark.
Key Takeaways
- U0123 indicates lost communication with the Yaw Rate Sensor Module.
- The fault is related to CAN Bus communication, not necessarily a failed sensor.
- Always check battery voltage, power, ground, and wiring before replacing modules.
- ESC, traction control, and ABS functions may be affected.
- Oscilloscope testing provides the most accurate CAN Bus diagnosis.
- Calibration may be required after sensor replacement.
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