Brembo A 00 377 Brake Pad Wear Sensor (Single) - Front and Rear Axle

The brake pad wear sensor is an electronic safety device that plugs into your brake pad. As the brake pad friction material wears down over time, the tip of the sensor eventually makes contact with the metal brake rotor. This completes (or breaks) an electrical circuit, triggering a warning light on your dashboard to let you know it is exactly the right time to replace your brake pads.

It is highly recommended not to reuse an old sensor. If your dashboard warning light has already come on, the sensor has physically worn down against the rotor and is permanently destroyed. Even if the light hasn't triggered yet, the plastic housing and wiring of the old sensor become extremely brittle from the constant heat of the brakes, meaning they almost always break when you try to remove them from the old pad.

It depends entirely on your specific vehicle's design. Most European vehicles (which commonly use electronic wear sensors) only use one sensor per axle - typically one on the front-left wheel and one on the rear-right wheel. However, some high-performance models may use a sensor on every single wheel. Always check your vehicle to confirm how many sensors are required before ordering.

In some vehicles, the light will turn off automatically after installing the new sensor and driving for a short distance. However, in many modern vehicles (such as BMW, Mercedes, and Audi), you must perform a manual reset procedure via the dashboard menu or use an OBD2 diagnostic tool to successfully clear the brake service warning light after a replacement.