What Are The Signs Of Worn Brake Pad Sensors?

Here are the two signs that indicate a worn-out brake sensor: 

1. Screeching Brakes

If your vehicle has a mechanical pad sensor installed on each brake pad, you may want to pay attention to any screeching or squealing sound on hitting your brake pedal. When that happens, it could indicate a worn brake pad.

In such a case, you should quickly get a brake service to replace the old pad and the worn-out brake pad sensor.

2. Brake Warning Light Turns On

Modern vehicles may use an electrical sensor that triggers the brake indicator light when its circuit breaks due to pad wear.

Some vehicles also have a two-wired electrical sensor with a resistor circuit that triggers multi-stage wear warnings via the brake light on your dashboard. These warnings are based on the degree of pad thickness.

Such wear sensors can also help estimate the remaining brake pad life by taking into account factors like:

• The brake temperature
• Brake pressure
• Driving style
• Pad material

So, if the brake warning light on your dashboard comes on, you should immediately take your vehicle for a brake service and get the necessary parts replaced if needed.  

How Much Does It Cost To Replace A Brake Pad Sensor?

The cost of aftermarket pads sensors can range between $5 to $100. And if you opt for a professional brake job, you can expect an additional labor cost of $70 to $100.

Moreover, several factors can add up to the cost of a new sensor, such as: 

1. Vehicle model and make 
2. Brake pad sensor brand and series
3. Brake sensor warranty
4. Pad sensor length
5. Wear sensor parts
6. City you live in

How Urgent Is A Brake Pad Sensor Replacement?

It’s typically not possible to reuse a pad sensor, and you should replace it at the earliest along with the old pad. 

Brake pad sensors are generally designed to break, so they should be replaced whenever new brake pads are fitted. More importantly, if your brake pad sensor sets off an alert, it also means you need new brake pads. 

Why?

If the friction material of a brake pad thins out completely, it can expose other brake parts to excessive wear. For example, the brake pad backing metal may grind against the brake rotor (also called a brake disc) and damage it. 

When that happens, your vehicle can lose its braking power and become a hazard on the road.

Such brake pad wear could also damage other crucial parts like the brake caliper. A caliper or rotor replacement can cost several hundred dollars above a brake pad replacement.

So, if you hear grinding or squealing noises from your front or rear brakes or if the brake warning light on your dashboard is illuminated, don’t take it lightly.

Moreover, if the brake pad wear is due to a sticking brake caliper, you may also need to get your caliper piston inspected and replaced, as it can fail to retract correctly after being out so far.

To prevent all this, you should have a new sensor installed with every new brake pad. It can alert you well in advance when you have a couple of hundred miles left to drive.

Some modern cars also have OEM pads with an in-built pad sensor. This means you don’t need to replace the sensor independently. You’ll just need to pay for one replacement, that’s to install a new pad.

3 FAQs On Brake Pad Sensors

Here’re answers to some common questions regarding brake pad wear sensors: 

1. What Is A Brake Pad Sensor?

A brake pad wear sensor or brake pad indicator is a safety feature in your vehicle. It can help keep track of your brake pad thickness and alert you when it’s time to get a pad replaced. 

Typically there are two types of brake wear sensors found on vehicles: 

1. Mechanical Wear Sensor.A mechanical sensor (also called a wear indicator) is a metal plate designed to come in contact with the rotor or brake disc when the wear has reached the desired pad thickness.So, when you hit your brake pedal and hear a sharp screeching sound, it’s your pad wear sensor indicating that it’s time for a brake pad replacement.
2. Electronic Wear Sensor
   An electronic pad wear sensor contains a resistor circuit that monitors the brake pad wear.

When the thickness of the pad material decreases, the sensor wire comes in contact with the rotor or brake disc. As a result, the circuit breaks and illuminates the brake indicator light on your dashboard. 

A vehicle can have one or more sensors installed (one on the front brake pad and a rear sensor on the rear brake pads). These sensors also come with their own software and algorithm to predict the brake pad life. 

Some vehicles may even have an electric pad wear sensor built into the OEM pads, or they could be attached separately to aftermarket pads.

2. When Do I Need A Brake Pad Sensor Replacement? 

Since a pad wear sensor is a part of your brake pad system, it doesn’t need to be replaced on its own.

You can simply get a new sensor installed whenever you get a new pad.

It’s also recommended to get your sensors inspected as a part of your regular brake service and allow a pad change when necessary. 

3. How Do I Change A Brake Pad Wear Sensor? (Step-By-Step) 

Whether you own a Mercedes-Benz, BMW, Volkswagen AG, or an Audi, replacing an electronic brake pad wear sensor as a DIY repair is not difficult. 

But hiring a professional mechanic or taking your car to the dealership for this brake job is always better. Wrong placement of any brake component can damage the whole braking system and endanger your safety on the road.

If you still plan to do the wear sensor replacement yourself, here are the steps to replace an electronic brake wear sensor.

Note: You should follow these steps once you’ve already replaced your brake pad.

1. Jack up the vehicle and remove the required wheel to expose the wheel hub. If replacing the rear brake pad wear sensor, jack up the passenger side (right rear) wheel. Likewise, jack up the driver’s side wheel if replacing the front sensor.

2. Locate the brake pad wear sensor. It’s usually installed within the inner brake pad of front or rear brakes. However, the number of brake pad sensors and their placement can vary from vehicle to vehicle.

3. Now, use a flat head screwdriver to pry out the old sensor.

4. Next, unhook the wear sensor from the brake caliper release valve.

5. Pull out the sensor wire from the strut bracket.

6. Open the black box mounted on the wheel well and pull the connector out of the box.

7. Press the release tab on the connector to separate the sensor wire.

8. Install the new sensor in reverse order. Ideally, you should get a sensor with the same part number as the old one. However, it’s not mandatory.

9. Set the wheel back on the car and remove the jack stand.

10. Once done, follow your vehicle’s OE-recommended repair procedure to reset the brake indicator light.