How to Check a Knock Sensor for Continuityby Johnathan Cronk
The knock sensor within your vehicle is a component designed to listen for engine detonation, or knocking. The knock sensor is a crucial part of the engine, as detonation is harmful to the engine; detonation is the result of fuel and air mixture exploding quickly instead of burning evenly. It's important that your engine knock sensor work properly to detect the detonation of the engine. The knock sensor should have continuity, which is a current electrical path between the wire and sensor. If continuity does not exist, the sensor cannot function properly; the sensor can be tested for continuity with a multimeter.
Park the vehicle on a level surface. Turn the engine off and engage the emergency brake. Open the hood of the vehicle and then turn the engine back on. It's best to engage the emergency brake and open the hood with the engine off to prevent possible injury.
Locate the knock sensor. The component is found on the engine manifold, mounted beneath the intake manifold in the middle of the engine. The knock sensor is connected with a wire harness coming out of the top. The location will vary slightly by manufacturer; refer to your repair manual for an exact diagram.
Disconnect the wire harness from the knock sensor. Pull on the base of the harness where it meets the sensor.
Clip the multimeter lead to the knock sensor; connect the negative multimeter lead to a ground point, such as the negative battery terminal. Continuity should exist, and the multimeter should read more than 10 ohms. If there is no continuity, the sensor should be replaced.
Items you will need
- Polka Dot Images/Polka Dot/Getty Images