Knock Sensors (KS) detect engine pre-detonation. They have 2 wires, one of which supplies a 5-volt reference and the other one supplies a return signal from the KS Sensor to the Powertrain Control Module (PCM). The sensor signal wire sends the data to the PCM when a knock occurs, as well as the degree. Then, the PCM delays the spark timing, thus preventing pre-detonation.
When the DTC P0333 OBDII code is set, it indicates that there is a high voltage at the output of the KS Sensor. This is greater than 4.5V, although this value may vary depending on vehicle make and model.
The Detonation Sensor circuit may have an open or is shorted to ground or voltage.
The KS Sensor may be incorrectly adjusted or faulty.
Fuel pressure may be too low.
The fuel supplied may be the wrong octane rating.
Possible solutions of the DTC code P0333 Generic
Troubleshooting steps related to the P0333 OBDII diagnostic code:
If you can hear the engine knocking, check for mechanical failures. Make sure you use the required octane of fuel.
Measure the resistance between the two terminals of the KS Sensor cable. Besides that, check the voltage across both terminals. All the readings obtained should be compared to the manufacturer's specifications.