How to Check
The PCM (Powertrain Control module) controls the ignition system spark advance and help it achieve maximum power with good fuel economy. The error code is triggered when the Knock Sensor informs the PCM about the knocking on the engine. The PCM then automatically changes the amount of timing advance by delaying it in measured increases. It continues to change until the knock sensor stops sending signal about the pinging or knocking to the PCM.
Error Code P0325 is triggered as the PCM identifies the signal from the Knock Sensor circuit, sensor #1.
To diagnose, take note of the freeze frame data so you will have an idea what operational conditions caused the PCM to trigger the error code.
Next, conduct a visual inspection on the engine and its cooling system, particularly the coolant level or the condition and oil level. This is to verify whether the error code was caused by a failure in the mechanical system or not.
Then, start the engine and make a few revolutions to see if it works normally. This is to ensure there are no severe mechanical errors that may affect the drivability of the vehicle and may cause further damage.
Then, test drive your vehicle. Bring a data streaming scanner with you and pay attention to the #1 Knock Sensor PID as well as the PID for timing advance. How is the sensor #1 working? Is it sending the signal to the engine when it pings? If not, then you should find out why. Sometimes, people tap the engine using a small hammer and observe the knock sensor PID, along with the PID for timing advance.