What Does This Error Mean?

The Subaru ABS warning light means the anti-lock braking system has detected a fault and disabled itself. Normal braking still works, but ABS will not activate during emergency stops. The most common cause is a failed or dirty wheel speed sensor — an OBD-II scanner reveals which one.

Affected Models

Subaru Outback
Subaru Forester
Subaru Impreza
Subaru Legacy
Subaru XV / Crosstrek
Subaru WRX
Subaru Ascent

Common Causes

Wheel speed sensor failed or dirty — the most common cause; Subaru's AWD system uses all four sensors constantly
Reluctor ring on the wheel hub cracked or corroded from road salt
ABS modulator unit fault — less common but more serious
ABS fuse blown
Low brake fluid level triggering combined warnings

How to Fix It

Read the ABS fault code with an OBD-II scanner.

Connect an OBD-II scanner to the port under the dashboard (driver's side). Subaru ABS codes appear as chassis C-codes — common codes include C0031, C0034, C0037 (wheel speed sensors), and C0044 (ABS solenoid). The code identifies exactly which wheel's sensor has failed — no guesswork needed.
Check if the VDC light is also on.

Subaru's VDC (Vehicle Dynamics Control) system shares wheel speed sensors with ABS — a failed sensor disables both systems, lighting both warning lights simultaneously. If the ABS and VDC lights are both on, a wheel speed sensor is almost certainly the cause. If only the ABS light is on, the fault is ABS-specific.
Inspect the wheel speed sensors.

Subaru wheel speed sensors sit at each wheel hub, particularly exposed on the front wheels. Remove the wheel and inspect the sensor body and wiring harness — look for corrosion, cracked insulation, or physical damage from road debris. Subaru wheel arches collect road mud and salt that corrodes sensor connectors over time — cleaning the connector with electrical contact cleaner often restores function.
Check the ABS fuse.

Open the engine bay fuse box and locate the ABS fuse — typically a 30A fuse. Replace a blown fuse with the same rating. A repeatedly blowing ABS fuse indicates a wiring short in the ABS circuit that must be professionally diagnosed.
Have the ABS modulator inspected on high-mileage vehicles.

On high-mileage Subaru Outbacks and Foresters, the ABS hydraulic modulator can develop internal solenoid faults that produce multiple simultaneous C-codes. A pattern of multiple sensor codes at once (all four wheels showing faults) suggests the ABS module rather than four individual sensors. ABS modules can often be rebuilt or replaced with a remanufactured unit at lower cost than a new OEM part.

When to Call a Professional

If the ABS warning and the Vehicle Dynamics Control (VDC) light are both on simultaneously, all stability systems are disabled. Have the fault code read to identify the specific component.