This part number supersedes to 98661236501 Genuine Porsche part 98661236500

Rear Brake Pad Wear Sensor 
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Maintain the safety and reliability of your Porsche braking system with this OE Match Rear Brake Pad Wear Sensor. Designed for Porsche 986 Boxster, Porsche 987.1 Boxster and Porsche 987.1 Cayman models, this sensor forms an integral part of the factory brake wear monitoring system, providing an early warning when rear brake pads have reached their service limit.

Fits:

• Porsche Boxster 986 2.5L 1997-99
• Porsche Boxster 986 2.7L 1999-02
• Porsche Boxster S 986 3.2L 1999-02
• Porsche Boxster 986 2.7L 2003-04
• Porsche Boxster S 986 3.2L 2003-04
• Porsche Boxster 987 S 3.2/3.4L 2005-08/08
• Porsche Boxster S 987 MKII 3.4L 2009-12
• Porsche Cayman S 3.4L 987C 2005-08
• Porsche Cayman S / R 3.4L 987C MKII 2009-12

Installed directly into the rear brake pad assembly, the sensor continuously monitors brake pad thickness. As the friction material wears down, the sensor activates the dashboard brake warning system, alerting the driver that replacement is required. This helps prevent excessive brake wear, protects brake discs and ensures the braking system continues to perform safely and efficiently.

For Porsche sports cars, maintaining the brake wear monitoring system is an important part of preventative maintenance and long-term braking performance.

What Does a Brake Pad Wear Sensor Do?

The brake pad wear sensor is designed to monitor the remaining thickness of the brake pad friction material.

As the brake pad wears, the sensor eventually contacts the brake disc and completes an electrical circuit, triggering the brake wear warning light on the dashboard.

A correctly functioning sensor helps:

• Monitor brake pad condition
• Provide early brake wear warnings
• Prevent excessive brake pad wear
• Protect brake discs from damage
• Improve service planning
• Support safe braking performance
• Maintain factory brake monitoring functionality

The sensor acts as an important safeguard, ensuring brake maintenance can be carried out before braking performance is affected.

Why Do Brake Pad Wear Sensors Fail?

Brake wear sensors operate in a challenging environment exposed to heat, vibration, moisture and brake dust.

Common causes of failure include:

• Normal brake pad wear
• Sensor activation after reaching its wear limit
• Damaged wiring
• Corrosion within electrical connections
• Heat-related deterioration
• Physical damage during brake servicing
• Water ingress
• Age-related component fatigue

Because the sensor is designed to function alongside the brake pad, replacement is generally recommended whenever new brake pads are installed.

When Should a Brake Pad Wear Sensor Be Replaced?

The sensor should be replaced whenever it has been activated, damaged or when brake pads are renewed.

Common symptoms include:

• Brake wear warning light illuminated
• Intermittent brake warning messages
• Damaged sensor wiring
• False brake wear alerts
• Corroded electrical connections
• Sensor damage during servicing
• Rear brake pad replacement due to wear

Replacing the sensor during brake maintenance ensures the warning system continues to operate correctly.

Why Replacement Matters

A functioning brake wear sensor helps maintain braking safety while reducing the risk of costly brake repairs.

Benefits include:

• Accurate brake pad monitoring
• Reliable warning light operation
• Improved braking safety
• Protection of brake discs
• Better maintenance scheduling
• Reduced repair costs
• Improved braking system reliability
• Long-term component protection

For Porsche Boxster and Cayman owners, maintaining the brake wear monitoring system helps preserve the safety and performance expected from the Porsche brand.