The P0327 code means that the Knock Sensor is not working properly. Problems with the knock sensor will not cause an engine performance problems. Replacing the knock sensor usually takes care of the problem.
When an engine operates, the Powertrain Control System (PCM) learns the minimum and maximum frequency of the noise the engine produces. When the PCM determines that this frequency is less than or greater than the expected amount, a knock sensor code will set.
Engine Light ON (or Service Engine Soon Warning Light)
Possible Lack/Loss of Power
P0327 Chevrolet Description
The Knock Sensor (KS) system monitors both knock sensors in order to determine if detonation is present. If the KS system determines that excessive knock (detonation) is present, the Powertrain Control System (PCM) retards the spark timing based on the signals from the KS system. When knock is present, the KS system voltage input signal to the PCM goes low. The PCM then retards timing until no knock is present.