Quick notes
- While you could take your car to a mechanic, replacing the brake pad sensor on a BMW E90 is a fairly straightforward DIY project that can save you some money.
- Use a flat-head screwdriver to release the clip holding the brake pad sensor wire to the brake caliper.
- After reconnecting the sensor wire, turn the ignition key to the “ON” position (without starting the engine) to see if the brake pad warning light goes off.
Are you hearing that annoying “brake pad sensor warning” chime in your BMW E90? It’s a telltale sign that your brake pads are nearing the end of their lifespan and need replacement. While you could take your car to a mechanic, replacing the brake pad sensor on a BMW E90 is a fairly straightforward DIY project that can save you some money. This comprehensive guide will walk you through the process, step-by-step, so you can confidently tackle this task yourself.
Understanding the Importance of Brake Pad Sensors
Before diving into the replacement procedure, it’s crucial to understand the role of brake pad sensors in your BMW E90. These small, electrical components are strategically located within the brake pad assembly. They act as early warning systems, detecting when the brake pads have worn down to a critical level. When the sensor triggers, it sends a signal to your car’s computer, which then activates the warning light and chime on your dashboard.
Ignoring this warning can lead to serious consequences. If your brake pads wear down completely, you risk damaging your brake rotors, which can lead to costly repairs. Additionally, driving with worn-out brake pads compromises your braking performance, putting your safety and the safety of others at risk.
Gathering the Necessary Tools and Materials
Before you begin, ensure you have the following tools and materials readily available:
- New brake pad sensor: Make sure you purchase a sensor specifically designed for your BMW E90 model year.
- Jack and jack stands: These are essential for safely lifting your car off the ground.
- Torque wrench: This is crucial for tightening the bolts to the correct specifications.
- Socket wrench set: You’ll need various sizes to remove and tighten bolts.
- Flat-head screwdriver: Used to release the sensor clip.
- Wire cutters: For cleanly removing the old sensor wire.
- Penetrating fluid (optional): This can help loosen stubborn bolts.
- Gloves: Protect your hands from dirt and grease.
- Safety glasses: Always wear safety glasses when working with tools.
Preparing Your BMW E90 for the Replacement
1. Park your car on a level surface: Ensure the parking brake is engaged and the car is in “Park” if you have an automatic transmission.
2. Chock the rear wheels: This will prevent your car from rolling while you are working on the front brakes.
3. Locate the brake pad sensor: The sensor is typically located on the inside of the brake caliper, near the brake pad. It will have a small wire running to it.
Replacing the Brake Pad Sensor: A Step-by-Step Guide
1. Remove the wheel: Use the jack to lift the car and secure it with jack stands. Remove the wheel using a lug wrench.
2. Locate the brake caliper: The brake caliper is the metal housing that holds the brake pads.
3. Release the brake caliper: Use a flat-head screwdriver to release the clip holding the brake pad sensor wire to the brake caliper.
4. Disconnect the sensor wire: Carefully disconnect the sensor wire from the brake caliper.
5. Remove the old sensor: Use wire cutters to carefully cut the old sensor wire close to the brake caliper.
6. Install the new sensor: Insert the new sensor into the same location as the old sensor. Make sure the sensor is properly seated and the wire is secure.
7. Reconnect the sensor wire: Connect the new sensor wire to the brake caliper.
8. Secure the sensor clip: Use the flat-head screwdriver to secure the sensor clip to the brake caliper.
9. Reinstall the wheel: Lower the car and reinstall the wheel, ensuring it is properly tightened.
Finalizing Your Brake Pad Sensor Replacement
1. Test the sensor: After reconnecting the sensor wire, turn the ignition key to the “ON” position (without starting the engine) to see if the brake pad warning light goes off.
2. Check for any leaks: Inspect the brake system for any leaks.
3. Take a test drive: Drive your car for a short distance to ensure the brakes are working properly.
Wrapping Up: A Job Well Done
Congratulations! You have successfully replaced the brake pad sensor on your BMW E90. By following these steps, you have not only saved money but also gained valuable experience in maintaining your vehicle.
Frequently Discussed Topics
Q1. How often should I replace brake pad sensors?
A1. Brake pad sensors are typically designed to trigger when the brake pads have worn down to about 5mm of remaining material. You should replace the sensor along with the brake pads.
Q2. Can I replace the brake pads without replacing the sensor?
A2. While it is technically possible, it is not recommended. The sensor is an important safety feature, and replacing it along with the brake pads ensures that your car’s warning system will function properly when your next set of brake pads wear down.
Q3. Can I reset the brake pad warning light myself?
A3. Some BMW models allow you to reset the warning light using the car’s onboard computer. Consult your owner’s manual or a reputable online resource for specific instructions on resetting the warning light for your BMW E90.
Q4. What if the brake pad warning light doesn‘t go off after replacing the sensor?
A4. If the warning light remains on, there could be a problem with the sensor itself, the wiring, or the brake pad wear sensor system. Consult a qualified mechanic to diagnose and fix the issue.