Knock Sensor KS4-R2

This sensor is used for detecting structural born vibrations in spark ignition engines due to uncontrolled combustion. This sensor is suitable for operation in extreme conditions.

Due to the inertia of the seismic mass, the sensor moves in correlation to the engine block vibration; this motion results in a compressive force which is converted into a voltage signal via a piezoceramic sensor element. As a result, upper and lower voltage thresholds can be defined directly correlating to an acceleration magnitude.

The main benefits of this sensor are its robust mechanical design, compact housing and precise determination of structure-related noise. This version is an optimized part for Motorsport applications based on a series application development. Compared to the previous version, the advantage of this new modification is that this product has an extended frequency and higher operating temperature rating.




  • Frequency: 3 to 30 kHz
  • Weight: 60 g
  • Height sensor head: 14 mm



3 to 30 kHz

Operating temperature range

-40 to 150°C

Storage temperature range

-30 to 60°C

Max. vibration

≤ 800 m/s2 at 0 to 24 kHz
≤ 4,000 m/s2 at 5 to 24 kHz (short-term)

Technical Specifications

Mechanical Data

Fixing screw for cast iron


Fixing screw for aluminum


Installation torque

20 + 5 Nm

Weight w/o Connector

60 g


IP 54

Electrical Data

Range of frequency

3 to 30 kHz

Max. sensitivity changing (lifetime)

-17 %

Linearity between 5 to 15 kHz (from 5 kHz value)

-10 to 10 %

Linearity between 15 to 20 kHz (linear increasing with freq)

20 to 50 %

Main resonance frequency

> 30 kHz

Ratio of frequency and sensitivity


> 1 MOhm

Temperature dependence of sensitivity

0.04 mV/g°C

Capacity field

1,150 ± 200 pF

Connectors and Wires



Mating connector


Pin 1


Pin 2


Pin 3




Wire size

0.5 mm2

Wire length L

150 to 450 mm

Various motorsport and automotive connectors on request.

Installation Notes

The KS4-R2 can be connected to all Bosch Motorsport ECUs featuring knock control.

The sensor must rest directly on the brass compression sleeve during operation.

To ensure low-resonance coupling of the sensor to the measurement location, the contact surface must be clean and properly machined to provide a secure flush mounting.

Please route the sensor wire in a way that prevents resonance vibration.

Please find further application hints in the offer drawing at our homepage.

Safety Note

The sensor is not intended to be used for safety related applications without appropriate measures for signal validation in the application system.

Ordering Information

Knock Sensor KS4-R2

Order number: F02U.V01.884-01

Legal Restrictions

Due to embargo restrictions, sale of this product in Russia, Belarus, Iran, Syria, and North Korea is prohibited.