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Posts Tagged: knock sensor

Chevrolet P0325

Diagnose and fix Chevrolet P0325 A Chevrolet P0325 refers to the engine knock sensor. The computer uses signals from the knock sensor to adjust engine timing to reduce detonation. A P0325 is defined as a problem with the Knock Sensor Circuit. Test a knock sensor on a Chevrolet On a late model Chevrolet, start by checking the knock sensor connector for damage. Next, open the connector and check for signs of corrosion. If the connector is in good shape with no corrosion, conduct the following tests. Using a digital multimeter, … Read More

Knock sensor

What does a knock sensor do? A knock sensor is really just a microphone that listens for abnormal engine noise caused by preignition or detonation. The sensor is tuned to a discrete frequency range so it doesn’t false alarm from normal engine noise. Most sensors use a piezoelectric material that generate a voltage when compressed. Why does the engine need a knock sensor? To get maximum power from each combustion event, engineers have determined that the combustion should reach maximum for at 14° after top dead center (TDC). To make … Read More

OBDII trouble Codes

OBDII trouble Codes I can’t tell you how many times forum members write in and say, “The computer said to replace the oxygen sensor. I replaced it and now it says to replace it again.” Let’s get one thing straight…..the computer NEVER says to replace a part. It only tell you what condition the OBDII trouble Codes. Here’s a typical example: P0137 – Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2) Now most of you would say the computer has determined that the oxygen sensor is bad. That’s NOT … Read More

P0332 Circuit Low Input (Bank 2)

Fix code P0332 Circuit Low Input (Bank 2) Also P0335 and P0340 If you think you should replace the knock sensor after getting this code, think again. This is a perfect example of where a sensor can be telling the truth and the root cause of the problem is somewhere else. Here’s the scoop. Most late model engine use variable valve timing to change the opening and closing timing of the valves. The device that actually changes the valve timing is called the cam phaser (yeah, like on Star Treck). … Read More


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