ABS and Traction Control Lights On - 2019 Crosstrek

ClearTheCode admin answer:

It's common for the ABS and Traction Control System (TCS) lights to illuminate together on your 2019 Subaru Crosstrek. This is because the TCS often relies on the same wheel speed sensor data as the ABS system. When one system detects an anomaly, it can disable both for safety. While your braking might feel normal, the ABS and TCS functions are likely disabled.

Here are the most common causes and diagnostic steps:

1. Faulty Wheel Speed Sensor (WSS): This is by far the most frequent culprit. Each wheel has a sensor that monitors its rotational speed. If a sensor fails, gets dirty, or its wiring is damaged, the ABS and TCS modules lose crucial data.
   • Common OBD-II Codes: Look for codes in the C0031-C0052 range (e.g., C0031 for Left Front WSS, C0034 for Right Front WSS, etc.). These indicate a circuit malfunction or incorrect signal from a specific wheel speed sensor.
   • Action: A scan tool can identify which sensor is faulty. Inspection involves checking the sensor for physical damage, cleanliness, and the integrity of its wiring harness.
2. Damaged ABS Tone Ring: The tone ring (or reluctor ring) is a toothed ring that the wheel speed sensor reads. If it's cracked, corroded, or damaged, it can send an incorrect signal.
   • Action: Visual inspection of the tone rings, which are often integrated into the wheel bearing assembly.
3. Low Brake Fluid Level: While less common for just ABS/TCS lights, extremely low brake fluid can sometimes trigger these warnings, along with the brake system warning light.
   • Action: Check your brake fluid reservoir level.
4. ABS Module Failure: Although less common than sensor issues, the ABS control module itself can fail. This is typically a more expensive repair.
   • Action: Diagnosis usually involves advanced scan tools and electrical testing by a professional.
5. Wiring Issues: Damaged or corroded wiring to the wheel speed sensors or ABS module can also cause these lights to come on.
   • Action: Thorough visual inspection of wiring harnesses, especially near the wheels.

When to See a Shop:

While the car might still brake, the absence of ABS and TCS can be dangerous in emergency braking situations or on slippery surfaces. It's crucial to get your Crosstrek diagnosed by a professional as soon as possible. They can use a specialized scan tool to read the specific ABS/TCS fault codes, which are often different from standard engine codes, and accurately pinpoint the problem. Driving without functioning ABS and TCS increases accident risk.