How To Test A Knock Sensor With & Without Multimeter

How To Test Knock Sensor With Multimeter

When the knock sensor fails, it will usually cause one or more significant symptoms. There are some methods to check whether the knock sensor is working correctly or not.  Below, those techniques are listed which must be performed before driving the vehicle, otherwise, the consequences may be worse, and it will harm the engine if the knock sensor was faulty.

The testing procedure is divided into two sections. First, the inspection can be done visually just by checking the parts and observing some precautions. While the second technique includes the testing via multimeter.

How To Test A Knock Sensor

1. By Visual Inspection

Visual Inspection Of The Car Engine
Visual Inspection Of The Car Engine

I. Inspection of DTC (Diagnostic Trouble Codes):

First of all, the technique is to inspect by Diagnostic Trouble Codes. By DTC, the testing procedure will be short, as it will show each and every fault. The DTC can be found out by OBD – II, which performs testing of each component, and the diagnosis process can be easy.

As, nowadays, all the vehicles are automatic and the systems are controlled by Engine Control Modules, that is why the use of OBD – II becomes crucial and the process has become very short for diagnosis. In the old car models, the code of the knock sensor problem is also stored as OBD – I. Nowadays, the OBD – II code readers can also be gotten on smartphones.

II. Checking for Damage in Cable Assembly:

The next process is to check for damage in any wire associated with the knock sensor. The cable assembly must be checked for damage if any. From the ECM to the knock sensor, the wires must be inspected for any defects. Fix that problem, check for DTC again, if the problem shows again or not.

Also, check for other defects, like, short circuits, wiring short circuits, mechanical damage to the wire, incorrect mounting, and corrosion in the wire and alongside the knock sensor.

How To Test A Knock Sensor With A Multimeter

How To Test A Knock Sensor With Multimeter
How To Test A Knock Sensor With Multimeter
  • First of all, engage the handbrake and turn off the engine. Wait for the engine to be cool if it is very hot.
  • Now, open the hood, and then after opening, turn the engine ON. It’s a precautionary measure, not to open the hood with the running engine.
  • After turning ON the engine, locate the knock sensor of the vehicle on the engine manifold. It’s commonly fixed to the middle of the engine below the intake manifold.
  • Have your manual for the car, mentioning all the precautions while locating the knock sensor, to avoid any mishap.
  • Find the cable assembly, with the knock sensor.
  • Disconnect the cable assembly from the knock sensor by pulling it from the base to the knock sensor.
  • Pick up the multimeter and connect its lead with the knock sensor.
  • Connect the negative terminal of the multimeter to the ground location. The resistance must be seen on the multimeter if there is no fault in the knock sensor, and it is working fine. The multimeter must-read resistance with the value of 93 to 110K ohms.

To do regular inspection of the vehicles is mandatory. Before going on the long drive, the knock sensor and the critical components must be inspected in order to avoid any uncertainty during the traveling.


Is there a way to test a knock sensor?

There are a few ways to test a knock sensor. One way is to use a multimeter to test the resistance of the sensor. Another way is to use an oscilloscope to test the output of the sensor and the third way is by doing a visual inspection.

What voltage does a knock sensor produce?

The knock sensor produces a voltage that depends on the severity of the knock. The sensor can produce a voltage between 0 and 4.5 volts. The voltage will be higher if the knock is more severe.

Can spark plugs cause knock sensor code?

There is a possibility that spark plugs can cause knock sensor code. If the spark plugs are fouled or worn out or do not fire correctly they can cause knocking or pinging sounds, which can trigger the knock sensor and can send a false signal to the ECU.

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