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U0123 — Lost Communication Yaw Rate Sensor Module

Generic OBD-II · all makesNetwork / communication

U0123 indicates that the vehicle's control module network has lost communication with the yaw rate sensor module. This sensor provides critical data for stability control, traction control, and rollover mitigation systems. When communication is interrupted, those safety systems may be disabled or operate in a reduced-function mode.

Symptoms

What causes it — most likely first

1. Yaw rate sensor module failure

Internal electronics or communication interface within the sensor module itself has failed, preventing it from transmitting data on the CAN bus.

2. Wiring harness damage or corrosion

Open circuits, short circuits, or corroded connectors in the power, ground, or CAN communication wires between the sensor module and the vehicle network.

3. Poor connector contact at sensor or gateway

Loose, bent, or contaminated terminals at the yaw rate sensor connector or at the body control/gateway module connector interrupting the CAN bus signal.

4. CAN bus fault or termination issue

Damage to the CAN high/low wires elsewhere on the bus, a faulty terminating resistor, or another module pulling the bus down can prevent communication with the yaw sensor.

5. Gateway or body control module fault

The module that routes CAN messages (gateway/BCM) may have a damaged communication port or internal fault preventing it from relaying yaw sensor data.

6. PCM/ECM communication fault

A fault in the powertrain or chassis control module's CAN interface is possible but rare; it should only be considered after all wiring, sensor, and gateway issues are ruled out.

How it's diagnosed

  1. Scan for all stored codes; note any additional U-codes indicating wider CAN bus issues.
  2. Visually inspect the yaw rate sensor connector and wiring for damage, corrosion, or loose terminals.
  3. Check power and ground at the yaw rate sensor module with a multimeter per service specifications.
  4. Measure CAN bus resistance (typically 60 ohms between CAN high and low with ignition off) to verify bus integrity.
  5. Use a scan tool to monitor live data; confirm whether the yaw sensor module is communicating or silent.
  6. If wiring and power/ground are good but no communication, replace the yaw rate sensor module and retest.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make
Related codesU0120 — Lost Communication Starter Generator CU0121 — Lost Communication Anti Lock Brake SysU0122 — Lost Communication Vehicle Dynamics CoU0124 — Lost Communication Lateral AcceleratioU0125 — Lost Communication Multi Axis AcceleraU0126 — Lost Communication Steering Angle Sens

Frequently asked

Will replacing the PCM/ECM fix U0123?

Almost never. U0123 is a communication loss with a specific sensor module; the root cause is typically the sensor module itself, its wiring, or the CAN bus. The PCM/ECM should only be considered after all other causes are eliminated.

Can I drive with U0123 active?

The vehicle will operate, but stability control, traction control, and rollover mitigation will likely be disabled. This reduces safety in emergency maneuvers or low-traction conditions; repair is recommended as soon as practical.

Does a dead battery or jump-start cause U0123?

A low-voltage event can set temporary communication codes. Clear the code after restoring proper voltage; if it returns, a hard fault exists.

Is the yaw rate sensor the same as the steering angle sensor?

No. The yaw rate sensor measures vehicle rotation around the vertical axis, while the steering angle sensor measures driver steering input. They are separate modules with separate codes.