Knock Sensor KS4-R

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. Connection to this sensor can be tailored to customer requirements through specified wire lengths and various connector options.




  • Frequency: 3 to 25 kHz
  • Weight: 82 g
  • Height sensor head: 18 mm



3 to 25 kHz

Operating temperature range

-40 to 130°C

Storage temperature range

-30 to 60°C

Max. vibration

≤ 800 m/s2

Technical Specifications

Mechanical Data

Male thread (for cast)


Male thread (for AI)


Installation torque

20 ± 5 Nm

Weight w/o wire

82 g


IP 54

Electrical Data

Range of frequency

3 to 25 kHz

Sensitivity at 5 kHz

28.8 mV/g

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


> 1 MOhm

Temperature dependence of sensitivity

0.04 mV/g°C

Capacity field

1,150 ± 200 pF

Connectors and Wires



Mating connector 2-pole

2-Pin RB-Kp.1 (D261.205.337-01)

Pin 1

Sig +

Pin 2

Sig -



Wire size

0.5 mm2

Wire length L

530 mm

Various motorsport and automotive connectors on request.

Installation Notes

The KS4-R 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-R


Order number: 0261.231.218

Legal Restrictions

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