C0108 DTC: Traction Control System Signal Invalid

OBD2 trouble code C0108 indicates that the ABS/Traction Control System (TCS) control module has received an invalid or implausible signal from one or more components used to control vehicle traction. Because the signal cannot be trusted, the module disables traction control and may also disable Electronic Stability Control (ESC).

What Does C0108 Mean?

The ABS/TCS module continuously compares wheel speed, steering angle, yaw rate, brake pressure, and engine torque data. If one of these signals falls outside the expected logical range or conflicts with other sensor inputs, DTC C0108 is stored.

Typical System Diagram

Wheel Speed Sensors
   │
Steering Angle Sensor
   │
Yaw Rate Sensor
   │
ABS / TCS Module
   ├── ECM / PCM
   ├── CAN Bus
   └── Instrument Cluster

Common Symptoms

• Traction Control warning light ON.
• ABS warning lamp illuminated.
• Electronic Stability Control disabled.
• Unexpected wheel spin.
• Poor traction on slippery roads.
• Additional ABS or CAN communication DTCs.

Possible Causes

• Faulty wheel speed sensor.
• Steering angle sensor out of calibration.
• Defective yaw rate sensor.
• Damaged tone ring.
• Loose or corroded wiring.
• CAN bus communication faults.
• Faulty ABS/TCS control module.

Driving Risk Level

Risk Level: Medium to High

The vehicle can usually be driven, but traction control and stability control may be unavailable. Vehicle stability may be reduced during emergency maneuvers or when driving on wet, icy, or gravel roads.

Diagnostic Flow Chart

Scan ABS Module

↓

Review Freeze Frame Data

↓

Compare Live Sensor Data

↓

Inspect Wiring And CAN Bus

↓

Repair Fault And Road Test

Oscilloscope Diagnostic Test

Use an oscilloscope to compare wheel speed sensor outputs and verify signal quality. Invalid signals typically contain distorted pulse widths, inconsistent amplitudes, or corrupted waveform patterns.

Normal Signal
__|‾|__|‾|__|‾|__|‾|__

Invalid Signal (Typical C0108)
__|‾|__||____|‾‾|_|__|‾

Waveform Analysis: Irregular pulse spacing and distorted amplitude indicate invalid sensor data being received by the ABS/TCS module.

Electrical Testing (Typical Values)

Battery Voltage	12.4–12.8 V
Charging Voltage	13.5–14.8 V
Ground Resistance	Less than 0.2 Ω

Scanner Live Data

• Individual Wheel Speed Values
• Steering Angle
• Yaw Rate
• Brake Pressure
• Traction Control Status
• CAN Communication Status

Estimated Repair Cost

Diagnostic Scan	$50–$120
Wheel Speed Sensor	$100–$350
Steering Angle Sensor Calibration	$80–$250
Yaw Rate Sensor Replacement	$250–$700
ABS Module Replacement	$500–$1,500+

Professional Diagnostic Tips

• Compare all wheel speed sensors during a road test.
• Verify steering angle sensor calibration.
• Inspect the tone rings for damage or debris.
• Check CAN network integrity before replacing modules.
• Use an oscilloscope to identify distorted sensor waveforms.

Common Repairs

• Replace faulty wheel speed sensors.
• Calibrate or replace the steering angle sensor.
• Replace a defective yaw rate sensor.
• Repair damaged wiring or connectors.
• Replace the ABS/TCS control module if required.

Related DTC Codes

• C0106 – Traction Control System Circuit Range/Performance
• C0107 – Traction Control System Signal Erratic
• C0110 – ABS Pump Motor Circuit
• C0245 – Wheel Speed Signal Malfunction
• U0121 – Lost Communication With ABS Control Module

FAQ

What usually causes C0108?

The most common causes are faulty wheel speed sensors, steering angle sensor calibration issues, yaw rate sensor faults, damaged tone rings, or CAN communication problems.

Can I drive with C0108?

Yes, but traction control and stability assistance may be disabled, reducing vehicle stability on low-traction surfaces. Prompt diagnosis is recommended.