DTC P0325 - Knock Sensor No. 1 Circuit Malfunction: Condition

WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.

DTC is set when input voltage front knock sensor is less than 1.25 volts or greater than 3.75 volts after engine is started. Possible causes are:

Knock sensor malfunction.
Incorrect sensor installation.
Open or short circuit between terminal "A" of knock sensor and terminal No. 3S on Engine Control Module (ECM).