U0128 Code: Lost Communication With Steering Angle Sensor Module

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What Is U0128 Code?

The U0128 code is an OBD-II communication fault code that indicates a lost connection between the vehicle control modules and the Steering Angle Sensor Module (SAS). This communication failure can affect safety systems that depend on accurate steering position information.

Code Description

The U0128 diagnostic trouble code indicates that a control module has lost communication with the steering angle sensor module through the CAN (Controller Area Network) system. The SAS provides steering wheel position data required by ABS, traction control, and electronic stability control systems.

Meaning of the Code

U0128 means the vehicle network cannot receive valid steering angle information from the SAS module. Without this data, some vehicle stability and safety systems may be disabled.

  • CAN communication interruption
  • Lost connection with SAS module
  • Missing steering angle data

Common Symptoms

  • ABS warning light
  • Traction control light ON
  • Electronic Stability Control warning
  • Steering angle data unavailable
  • Vehicle stability system malfunction
  • Warning messages on dashboard

Possible Causes

  • Faulty steering angle sensor module
  • Open or shorted CAN communication wires
  • Corroded or loose connectors
  • Low battery voltage
  • Blown SAS module fuse
  • Faulty ABS or body control module
  • Module software or calibration problem

How Serious Is It?

Severity: Moderate to High
U0128 can disable important stability and traction systems. The vehicle may still operate, but safety assistance features may not function correctly.

Diagnostic Steps

  1. Scan all control modules and record communication-related codes.
  2. Check battery voltage and charging system performance.
  3. Inspect steering angle sensor connectors and wiring.
  4. Test CAN High and CAN Low circuits.
  5. Verify SAS module power and ground supply.
  6. Check steering angle sensor live data with a scan tool.
  7. Perform calibration after repair if required.

Common Repairs

  • Repair CAN wiring faults
  • Clean or replace damaged connectors
  • Replace steering angle sensor module
  • Repair power and ground circuits
  • Update or program control modules
  • Perform steering angle calibration

Repair Cost

Repair Estimated Cost
CAN wiring repair $50 - $200
Connector repair $50 - $150
Steering angle sensor replacement $200 - $800
Module programming $100 - $500

FAQ

Can I drive with U0128 code?

The vehicle may drive, but stability control, traction control, or ABS-related functions may be affected.

What causes U0128?

The most common causes are CAN communication faults, wiring problems, low voltage, or a failed SAS module.

Does replacing the steering angle sensor fix U0128?

Not always. The communication network and electrical supply should be tested before replacing the sensor.

How do I clear U0128?

Fix the cause of the communication failure, clear the code with an OBD-II scanner, and verify normal operation.

Related Codes

  • U0126 - Lost Communication With Steering Angle Sensor Module
  • U0127 - Lost Communication With Steering Angle Sensor Module
  • U0121 - Lost Communication With ABS Control Module
  • U0100 - Lost Communication With ECM/PCM

Conclusion

The U0128 code indicates a communication failure involving the steering angle sensor system. A complete diagnosis should focus on CAN network integrity, wiring, power supply, connectors, and module operation before replacing components.

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