By iCarsoft Official Store Technical Team, Automotive Diagnostics Editors · Updated October 13, 2026 · OEM technical references checked
Quick Answer
U0123 describes lost communication with yaw rate sensor module in the documented application. It does not prove a failed yaw sensor, ABS/VSC controller or universal calibration fault. Save the original scan, confirm VIN scope and use approved multi-module network tests before choosing a repair.
What Does the U0123 Code Mean?
For the documented application, U0123 concerns lost communication with yaw rate sensor module. Confirm the vehicle, reporting module and full wording before using this guide. The full fault record determines the test branch.
U0123 identifies lost communication with a yaw-rate sensor module. Yaw describes the vehicle's rotation about its vertical axis. The fault concerns delivery of the expected module information; it does not, by itself, say that the vehicle rotated unexpectedly or that the sensor measured an incorrect yaw rate. Keep a missing message separate from a present but implausible sensor value.
Find the yaw sensor's physical and network arrangement in the vehicle information. It may be part of a combined sensing assembly rather than a separately replaceable component. The reporting brake or stability controller can differ from the assembly named by the generic code. Record both identities, the full suffix and whether the expected sender appears in a supported system scan.
Check recent interior, wiring, sensor or calibration work without assuming it caused the event. Connector seating, mounting and setup requirements depend on the identified assembly. Do not substitute a calibration for a missing feed or communication path. Conversely, restoring communication does not automatically prove that the sensor's orientation and calibration are correct. Compare the manufacturer's required final data and functional checks after the proven repair.
Do not induce a skid or abrupt maneuver on public roads to test yaw sensing.
A yaw-related handoff should retain the sensor identity and the source of each displayed value. State whether the information was absent, present but flagged invalid, or present under the manufacturer's approved check conditions. Those results support different follow-up decisions. Record any installation or calibration work separately from a repair to a feed or network branch.
Do not label a zero-point procedure successful unless its stated prerequisites and completion indication were met. If another dynamics-sensor code remains, compare its sender and receiver before assuming a second sensor failed. This record helps prevent an unnecessary sensor replacement after communication has already been restored.
Communication loss is distinct from an implausible yaw signal or unfinished calibration.
NHTSA's Functional Safety Assessment of an Automated Lane Centering System, Appendices, lists U0123 as lost communication with a yaw-rate sensor module. This supports the code terminology; the assessment is not a VIN-specific workshop procedure or proof of a particular repair.
Keep yaw-rate message delivery, measured signal plausibility and calibration status as separate findings. Use the vehicle diagram to identify the sender and receiving controller before choosing a test. The NHTSA terminology list does not identify the installed assembly or prescribe its replacement. A missing message cannot be repaired merely by assuming that a calibration is due.
Save the full module wording and suffix before clearing; they can change the test path.
Separate U0123 from adjacent fault families
| Code | General description | Key distinction |
|---|---|---|
| U0123 | Lost Communication with Yaw Rate Sensor Module | This guide’s documented application; retain the full suffix. |
| U0121 | Lost Communication with ABS/Brake Control Module | A different module path; compare the reporting controller and vehicle function. |
| U0140 | Lost Communication with Body Control Module | A body-network code is not interchangeable with this module-specific result. |
Record the complete U0123 description. The suffix, reporting module and companion faults can change the diagnostic path. Use the manufacturer's full wording and test procedure for the exact vehicle.
U0123 Symptoms and Likely Causes
Record U0123 symptoms and fault status; symptoms alone cannot identify a failed part.
Check whether companion faults share a proven cause.
Record the exact warning, when it appeared and which function changed; it is evidence, not proof of a failed module.
Compare saved multi-module reports with supported live data; unavailable data does not identify the cause.
Preserve the service history and inspect the disturbed branch first, while treating timing as a clue.
Save every module’s codes and status; a shared supply or network code can change the diagnostic order.
Practical cause-checking order
- Power, ground, connector or wake-state problem affecting the communication path: Low-voltage supply, ground or wake-state loss
- Open, shorted, corroded, chafed or water-damaged network wiring: CAN wiring, connector, termination or gateway interruption
- Gateway, termination, configuration or software condition: Configuration or software mismatch after module work
- Module intentionally asleep, isolated or unavailable during service: Service or isolation state blocking expected messages
- Internal controller fault only after external branches pass: Controller fault after external communication checks
Did U0123 appear after recent battery, module, harness, gateway or programming work? Recheck the documented connections, parts and setup steps affected by that work. Record battery and software history; a post-repair code does not prove the new part is defective.
How Serious Is U0123, and Can You Drive?
Follow the actual brake and stability warnings and the owner manual. The yaw-module communication record cannot establish a safe driving distance or certify stability assistance. Stop for abnormal braking, handling or a red stop warning. Do not reproduce a skid or abrupt turn to test the sensor.
Record warning messages, operating conditions and service history. Do not induce wheel slip, emergency braking or a handling event on public roads. A red stop warning or abnormal control overrides any verification plan.
Stop and arrange a tow if steering, braking, propulsion, charging, parking-brake or other safety behavior is abnormal.
Follow the vehicle-specific brake and stability-system service precautions. Do not bypass interlocks, probe restraint circuits or command powered safety components outside the approved procedure.
How to Diagnose U0123 in the Right Order
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Identify the application and preserve evidence
Save the receiver module, U0123 status, stability warnings, yaw/steering/lateral codes and calibration history before clearing.
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Inspect the relevant physical and electrical path
Use the VIN service diagram to identify the yaw sensor module, receiver, power/ground circuits, CAN segment, mounting direction and calibration requirement.
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Confirm architecture and prerequisites
Inspect the sensor connector, terminals, ground, harness and mounting only after securing the vehicle; do not disturb the sensor orientation casually.
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Separate network behavior from system behavior
Prove module wake and CAN communication, then compare whether the receiver sees the sensor; a missing message is not an implausible yaw value.
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Prove the repair path before parts
Once communication is stable, perform the specified zero-point or dynamic calibration on a level vehicle and verify the returned data against OEM conditions.
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Verify the original condition after repair
Reread all stability modules, confirm warnings are absent and verify brake/stability readiness without inducing an unsafe maneuver.
Specifications are vehicle-specific. Use the exact VIN specifications, approved test points and required operating state. No generic value or drive cycle can replace the applicable procedure. Manufacturer examples here do not establish specifications for other applications.
U0123 Repairs and Cost Planning
A U0123 repair must address the demonstrated failure. Do not replace an assembly from the code alone.
Recheck installation and required setup after repair. The receiver and network segment must be named from the VIN diagram before probing.
Ask the shop to name the failed branch and the measurement supporting each proposed repair.
Authorize diagnosis before parts while the cause remains uncertain.
| Possible path | Quote basis |
|---|---|
| Repair the demonstrated power, ground, connector, harness, gateway or network branch | VIN-specific quote |
| Restore configuration, software or required setup only through the VIN-specific procedure | VIN-specific quote |
| Replace the isolated controller or assembly only after external evidence and the OEM test support that path | VIN-specific quote |
These are alternative repair paths, not prices to add together. Request a VIN-specific quote separating diagnosis, parts, labor, fluids, taxes, required setup and verification. Ask which failed test supports the proposed repair and whether warranty coverage applies.
Using iCarsoft CR Eagle P for U0123
On a supported vehicle, iCarsoft CR Eagle P can save accessible faults, available freeze frame, live data and diagnostic reports. Preserve the U0123 evidence before clearing.
Compare the saved and final module records. Scan data supports diagnosis but does not replace the OEM reference, physical measurement or safety-system functional check.
Preserve the yaw-rate sensor module communication, mounting, CAN path and calibration evidence
iCarsoft CR Eagle P
Review supported codes and relevant live data together. Confirm the exact VIN, controller access, PIDs and any requested active test with iCarsoft before purchase; generic product capabilities do not guarantee a U0123-specific function.
Check current CR Eagle P price and availabilityCheck CR Eagle P compatibility by VINThe official product page describes supported full-system diagnostics, available live data, freeze frame and diagnostic reports; exact controller coverage and active tests depend on the VIN and software. Confirm the requested function by VIN before purchase. Follow OEM prerequisites and stop for abnormal operation.
Know the measurement boundary. Scan data describes ECU-provided information; it does not directly prove the physical condition of the yaw-rate sensor module communication, mounting, CAN path and calibration. Where required, use approved multi-module scan access, wiring diagram, voltage-drop/continuity tools and the VIN-specific network procedure and compare reported values with the relevant measured evidence.
Verify the U0123 Repair
After repair, verify installation, clearance and required setup. Save the final findings and clear only erasable records as instructed. Battery disconnection is not a repair.
Run the manufacturer's applicable verification conditions in a safe workshop or route. Compare the original operating state with current data for the yaw-rate sensor module communication, mounting, CAN path and calibration, and check current and pending faults in related modules. A clean start or idle period does not prove the repair; use the OEM functional check for the affected system.
Compare the original and final fault status. Record the functional-check result and whether the original event returned.
If U0123 returns, compare its suffix, status, failure order and operating conditions with the saved baseline before replacing another part. Revisit the failed branch and inspect anything disturbed. Confirm the prescribed affected-system functional verification separately from code clearing.
Verification follows the system involved. After saving the original evidence, use the OEM procedure to clear erasable records, complete any required calibration or functional check, and compare the final module status with the original warning and fault conditions.
Related Yaw-Rate Sensor Module Communication, Mounting, CAN Path And Calibration Code Guides
Compare the related monitor families below. Shared symptoms or components do not make their repair procedures interchangeable.
U0123 Frequently Asked Questions
Does U0123 prove the named module is bad?
No. U0123 describes lost communication with yaw rate sensor module, not a confirmed part. Use the manufacturer’s network and module tests to distinguish power, wiring, gateway, software and controller branches before replacing parts.
What should I check first for U0123?
Save every module's codes and freeze frame before clearing. Confirm the full definition, suffix and VIN architecture. Then inspect recent battery, module, harness, gateway or programming work, connectors and shared supplies. Those facts determine whether the next test needs approved multi-module scan access, wiring diagram, voltage-drop/continuity tools and the VIN-specific network procedure or a manufacturer-specific functional procedure.
Can I drive with the U0123 code?
Follow the actual brake and stability warnings and the owner manual. The yaw-module communication record cannot establish a safe driving distance or certify stability assistance. Stop for abnormal braking, handling or a red stop warning. Do not reproduce a skid or abrupt turn to test the sensor.
Why did U0123 return after a part was replaced?
A clear code cannot certify VSC/ABS safety or sensor calibration.
What should a U0123 repair estimate include?
Ask for the failed-test evidence and a VIN-specific breakdown of diagnosis, parts, labor, taxes, required setup and verification. A code alone cannot establish the repair price.
Can CR Eagle P diagnose and clear U0123?
On a supported vehicle, CR Eagle P can organize available faults, freeze frame, live data and reports, and can clear erasable records after repair. Confirm exact ECU coverage. It cannot replace the OEM functional procedure or physical measurements for the yaw-rate sensor module communication, mounting, CAN path and calibration.
The iCarsoft Official Store Technical Team maintains the store's fault-code library. This guide organizes published technical references and verified product information; it does not document a hands-on test of a particular vehicle or claim an individual engineer's review.
Technical and cost references
- NHTSA DOT HS 812 573 — Functional Safety Assessment of an Automated Lane Centering System: Appendices, Appendix K. Code terminology and associated sensor/control function; not VIN-specific diagnosis or a repair authorization.
- Subaru Technician Reference Booklet MSA5P0135C — Electrical Systems Operation & Diagnosis, Module 602, June 2013. OEM network-training context. Subaru examples do not establish another vehicle’s topology, specifications or fail-safe behavior.
Product information: Official iCarsoft CR Eagle P page.
Editorial note: General diagnostic education, not a substitute for the owner's manual, current VIN-specific service information or professional inspection. Test limits, procedures, coverage and costs vary. Related articles provide context; apply only the specifications and repair procedures that match the vehicle. No universal failure rate, repair price or outcome is implied.
