How To Test A Knock Sensor With Multimeter

Are you looking to test your car’s knock sensor using a multimeter? If so, the good news is that it’s quite simple. In this article, we will provide you with expert tips and advice on identifying or diagnosing any issues related to the knock sensor in your vehicle. By utilizing our step-by-step guide for testing a knock sensor with a multimeter, you can easily spot any problems concerning the knocking that goes on inside an engine and take corrective action as needed. So read on to find out more!


Symptoms Of a Bad Knock Sensor

  • Poor engine performance, including lack of power and acceleration.
  • Increase exhaust emissions such as HC, CO, and NOx to higher than normal levels.
  • Increase in fuel consumption due to poor combustions caused by misfiring.
  • The engine produces a decrease in maximum torque at higher rpm levels.
  • Knocking or pinging noise from the engine when accelerating or under load (also known as detonation).
  • Check the Engine Light illuminated on the dashboard for diagnostic trouble codes of knock sensor failure or related components such as ignition coils or cylinders with weak spark plugs fired by a damaged knock sensor signal circuit.
  • Misfires were detected during a comprehensive vehicle diagnostic test.
  • Rough idle, especially when the engine is warm or cold-starting after a short period of rest.
  • Detonation detected during an internal combustion (Cylinder Pressure Analysis) test.
  • A sudden loss in fuel efficiency and performance due to incorrect ignition timing was caused by inaccurate readings from the Knock sensor’s signal circuit to the ECU (Engine Control Unit).

Each of these symptoms can be indicative of a bad knock sensor and should not be ignored. If you experience any of the above, have your car’s knock sensor inspected as soon as possible to prevent further engine damage.

How To Test A Knock Sensor With Multimeter

Testing a knock sensor is essential for ensuring the proper functioning of your vehicle’s engine. A faulty knock sensor can lead to decreased performance and a misfire, so it’s vital to diagnose and repair any issues as soon as possible.

  • Remove the engine hood to locate the knock sensor.
  • Disconnect the sensor from its wiring harness and connectors.
  • Connect one multimeter probe to each of the two terminals on the knock sensor.
  • Look at the reading on your digital multimeter; if you see continuity and it reads more than 10 OHMs, then your knock sensor is suitable; otherwise, if there are issues with its wires, you’ll see an “OL” (open line) displayed instead.
  • Set your multimeter to DC voltage mode and connect one multimeter probe to each of the two terminals on the knock sensor again.
  • Start your vehicle’s engine for the ECU to activate the knock sensor and produce a voltage reading.
  • Record the voltage being supplied to the knock sensor; if it is between 0.2V – 6V, then your knock sensor is functioning correctly.

An incorrect result could indicate an issue with either wiring or the Knock Sensor itself, in which case you should replace it as soon as possible. Following these steps, you can quickly test your knock sensor with a multimeter, ensuring that your vehicle’s engine runs smoothly and efficiently.

Tips for preventing future problems with your knock sensor

  • Check your knock sensor regularly to ensure it is functioning correctly and not malfunctioning.
  • If the knock sensor is failing, replace it as soon as possible. Neglecting to do so can cause more damage in the future.
  • Ensure you always use high-quality gasoline with a minimum octane rating of 91 or higher for your vehicle. This can help reduce engine knocking and protect the knock sensor from damage caused by low-octane fuel.
  • Regularly maintain your engine to prevent dirt and deposits from building up on critical components such as spark plugs, valves, and pistons which can all lead to increased knocking and cause stress on the knock sensor.
  • If your vehicle’s engine is misfiring, have it inspected and repaired as soon as possible to prevent further damage to the knock sensor.
  • Always use the manufacturer’s recommended oil type and weight for your vehicle’s engine so that all its components remain lubricated, including the knock sensor.
  • Keep a close eye on your car’s timing belt as well; if it breaks, the resulting problem can cause serious damage to the knock sensor.
  • Lastly, please pay attention to any unusual noises coming from your engine when you start it up or when driving and take care of them promptly, as this may indicate problems with the knock sensor.

Following these tips can help you prevent future problems with your knock sensor and keep it working correctly for many years. Consult a professional mechanic if you have questions about maintaining your knock sensor.

read more: How To Test 3 Wire Crank Sensor With Multimeter

Frequently Asked Questions:

What voltage should be present at a knock sensor?

When testing a knock sensor with a multimeter, you should expect to see voltage spikes ranging from 0-4.5 volts. The voltage will be determined by the condition and type of knock sensor being tested. If the readings are outside of this range, it could mean that the sensor is broken or needs to be replaced. Specific testing instructions and expected voltage ranges for your specific make and model must be found in your vehicle’s service manual. Furthermore, suppose the reading does not change when you knock on the engine block. In that case, there could be a problem with the wiring harness or the connection to the ECU (Engine Control Unit) that needs to be looked into further.

What is the resistance range of a knock sensor?

The resistance range of a knock sensor varies depending on its type and condition. High-quality sensors should generally have an approximate resistance reading of 0-10. (Ohms). Any readings outside this range may indicate that the sensor must be replaced. As always, consult your vehicle’s service manual for specific instructions on testing and troubleshooting your specific make and model. Furthermore, if there are discrepancies between the service manual and the results you are seeing, you should seek the assistance of a qualified technician.

How can I tell if my knock sensor is defective?

Defective knock sensors can be identified by their response to engine noise or vibration. If the multimeter reads 0 volts when the engine is running, and there is no change in voltage when knocking on the engine block, it could indicate a faulty sensor. Additionally, suppose the readings taken with a multimeter are outside of your vehicle’s expected range as specified in its service manual. In that case, this could also point toward a malfunctioning or worn-out sensor.


Finally, using a multimeter to test a knock sensor is simple and quick. The testing procedure is connecting the multimeter to the two pins of the knock sensor and checking for continuity between them while the engine is running. If there is continuity, the knock sensor is functioning correctly. Other issues, such as corrosion or breaks in the wiring leading to or from the sensor, should also be investigated. Furthermore, before running this test, ensure that all connections are secure. With this knowledge, you should be able to test a knock sensor with a multimeter more effectively.

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