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P0333 OBD-II Trouble Code: Knock Sensor 2 Circuit High Input (Bank 2)

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P0333 code definition

The P0333 code indicates that your car’s computer has detected an input reading for one cylinder’s knock sensor circuit that goes beyond the manufacturer’s limit.

What the P0333 code means

The P0333 code means that the input voltage from a knock sensor circuit in one of the cylinders on bank 2 is higher than the manufacturer’s limitation. In most instances, a 10% variation is needed for this code to set. However, your vehicle will likely require multiple instances to set the code. Knock sensors alert the car’s computer to unusual engine noise, generally caused by an incorrect air-to-fuel ratio, which can lead to detonation and damage within a cylinder. This code is usually seen in conjunction with other, more serious issues.

What causes the P0333 code?

A number of potential causes can make the computer set a P0333 code. These include the following:

  • Faulty knock sensor (most often seen when the engine is running quietly)
  • Corroded connectors
  • Frayed wiring
  • Broken sensor during starter replacement

What are the symptoms of the P0333 code?

You may notice a number of different symptoms if the computer stores the P0333 code. These include:

  • The Check Engine Light coming on and staying on, staying on and then turning off, or turning on and off at different intervals
  • Lack of power on acceleration
  • Engine knocking
  • Reduced engine power

How does a mechanic diagnose the P0333 code?

First, the mechanic will connect an OBD II scanner to the car’s communication port and check the codes stored. Next, a test drive is needed to verify that the code returns and to listen for abnormal engine noise or check for unusual operation.

If another, more serious engine code is stored in the computer, then the mechanic will troubleshoot that code first, as the P0333 code is often caused by other problems, and the knock sensor is actually not faulty.

If there are no other codes, the mechanic will inspect the knock sensor’s wiring harness for signs of fraying or damage. The mechanic will also check for loose connections or disconnected plugs. If no problems are found here, the knock sensor itself will be checked. Sometimes, in engines where the sensor is mounted near the starter, it can be damaged or broken during starter replacement. In other instances, the knock sensor may have failed and replacement will be necessary.

Common mistakes when diagnosing the P0333 code

The most common mistake in this instance is replacing the knock sensor when it is not actually faulty. If a more serious engine code is present in conjunction with the P0333 code, troubleshoot the other code first.

How serious is the P0333 code?

While the P0333 code will not always result in drivability problems, it is important to have it inspected immediately. The main reason for this is that the code can be caused by more serious engine problems, which can lead to serious damage and higher repair costs.

What repairs can fix the P0333 code?

The repair needed to fix the P0333 code will vary depending on the underlying cause of the problem. However, the following may be needed:

  • Repair or replacement of damaged wiring
  • Repair or reconnection of damaged connectors or unplugged connectors
  • Repair of more serious engine problems causing the P0333 code to set
  • Replacement of the knock sensor

Additional comments for consideration regarding the P0333 code

It is important for mechanics to conduct a full diagnostic in this instance. While it is possible that the knock sensor has failed, there may be a more serious problem. It is also important to ensure that the wiring and connectors are checked, as these are more often the problem than a failed sensor.

Need help with a P0333 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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