Chevrolet P0325

Diagnose and fix Chevrolet P0325

A Chevrolet P0325 refers to the engine knock sensor. The computer uses signals from the knock sensor to adjust engine timing to reduce detonation. A P0325 is defined as a problem with the Knock Sensor Circuit.

Test a knock sensor on a Chevrolet

On a late model Chevrolet, start by checking the knock sensor connector for damage. Next, open the connector and check for signs of corrosion. If the connector is in good shape with no corrosion, conduct the following tests.

Using a digital multimeter, connect one lead to the Black/Yellow pin terminal and the other to ground. With the key ON but engine Off, you should see 1-2 volts.

Next, connect one lead to the Violet/Gray wire with the other to ground. You should see 2-4 volts.

If the voltage checks out, the circuit to the knock sensor is good and the sensor is bad…..potentially (more on that below).

If the voltages don’t check out, trace bad to the ECM to find the open/short.

How to replace a Chevrolet P0325 knock sensor.

Locate the knock sensor and remove the old one. Install the new sensor and torque to 18-ft/lbs. on the Chevrolet 1.4L engine. Check the specs for other engines.

Other causes of P0325L

Keep in mind that the knock sensor can’t tell the difference between shock waves from detonation and shock waves from any other mechanical condition. In the case of late-model Chevrolet 1.4L engines, some shops are reporting a Chevrolet P0325 even after replacing the knock sensor. Further testing has shown that loose timing chain guide bolts tend to loosen, causing the guide to vibration and bounce when the engine is running.

©, 2020 Rick Muscoplat