These sensors have a pretty important job to do. These sensors tell your car how fast the wheels are rotating, this is then checked against the vehicle speed. 

If one wheel is spinning faster than the others then the ABS module will apply the brakes to that wheel to slow it down. 

If the wheel is registered as spinning slower or not spinning at all, then the ABS module will take steps to stabilise the wheel.

What is an ABS / Wheel Speed Sensor?

It is a small electrical sensor that is mounted to the wheel hub, wheel rotor, differential or steering knuckle.

There is a toothed wheel and a magnet inside a coil. As the wheel spins, this rotates the toothed wheel which contacts the magnet and produces an electric field which generates a signal.

It’s this signal that is sent to the ABS module/engine control unit from all four wheels that make up your ABS system.

Why do you need an ABS / Wheel Speed Sensor?

When you’re driving in poor conditions like wet roads, snow, ice, gravel etc. If your car loses traction, the wheel speeds on one side or one corner will be different compared to the others. 

This is when, based on the sensors, the ABS module or ECU will ‘brake’ the required wheels and regain traction. 

If you lose traction while braking, the sensor will send the signal to the ABS module or ECU that the wheel has locked up. The ABS module will then lower the braking force applied to the wheel and allow it to rotate again. 

What symptoms mean your Subaru needs a new ABS / Wheel Speed Sensor?

• Your ABS warning light is illuminated or the traction control light stays on
• Your ABS will trigger at random intervals, even under light braking
• The ABS will fail to stop the wheels locking up

How is an ABS / Wheel Speed Sensor replaced? 

• Mechanic assesses which sensor/’s are failing 
• Wheel is loosened and the car is lifted on a hoist
• The sensor connector is disconnected 
• The sensor is removed 
• If the sensor is part of the hub assembly then it will need to be replaced as part of the whole assembly
• The new sensor is fitted and tested
• The wheel is refitted and the car is dropped down off of the hoist
• The mechanic will check all codes are cleared and perform a road test to ensure that everything is working correctly

How much does an ABS / wheel speed sensor replacement cost for my Subaru?

The costs can vary depending on whether the sensor can be replaced without needing too much disassembly. Typically expect prices from $350 to upwards of $700 for a full hub assembly replacement.

How often does my Subaru need a new ABS / Wheel Speed sensor?

Typically these fail after 100,000km but sometimes can live to beyond 150,000km in some cars. They are only replaced when they fail or stop performing as they should.

Is a broken ABS / Wheel Speed sensor unsafe?

Yes, if it negatively affects your braking and safety then it is absolutely unsafe. Listen to your warning lights and don’t risk it.

You can find a Subaru ABS/Wheel Speed Sensor Replacement mechanic near me with My Auto Shop