Wiring Diagram:

WARNING: This page is about a different variant/trim than selected.

Fig 1: Wiring Diagram - DTC P0328 Knock Sensor 1 Circuit High Input (Bank 1 Or Single Sensor)

Courtesy of SUBARU OF AMERICA, INC.

DTC P0328 DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1. CHECK HARNESS BETWEEN KNOCK SENSOR AND ECM CONNECTOR. Measure the resistance of harness between ECM connector and chassis ground. Connector & terminal (B136) No. 25 - Chassis ground:	Is the resistance less than 400 kΩ?	Go to step 2.	Go to step 3.
2. CHECK KNOCK SENSOR. Disconnect the connector from knock sensor. Measure the resistance between knock sensor connector terminal and engine ground. Terminals No. 2 - Engine ground:	Is the resistance less than 400 kΩ?	Replace the knock sensor. < Ref. to KNOCK SENSOR . >	Repair ground short circuit in harness between knock sensor connector and ECM connector. NOTE: The harness between both connectors is shielded. Repair short circuit of harness together with shield.
3. CHECK INPUT SIGNAL FOR ECM. Connect the connectors to ECM and knock sensor. Turn the ignition switch to ON. Measure the voltage between ECM and chassis ground. Connector & terminal (B136) 25 (+) - Chassis ground (-):	Is the voltage more than 2 V?	Even if malfunction indicator light lights up, the circuit has returned to a normal condition at this time. (However, the possibility of poor contact still remains.) NOTE: In this case, repair the following: Poor contact in knock sensor connector Poor contact in ECM connector Poor contact in coupling connector	Repair poor contact in ECM connector.

Step

Check

Yes

1. CHECK HARNESS BETWEEN KNOCK SENSOR AND ECM CONNECTOR.
Measure the resistance of harness between ECM connector and chassis ground.

Connector & terminal

(B136) No. 25 - Chassis ground:

Is the resistance less than 400 kΩ?

Go to step 2.

Go to step 3.

2. CHECK KNOCK SENSOR.

Disconnect the connector from knock sensor.
Measure the resistance between knock sensor connector terminal and engine ground.
Terminals

No. 2 - Engine ground:

Is the resistance less than 400 kΩ?

Replace the knock sensor. < Ref. to KNOCK SENSOR . >

Repair ground short circuit in harness between knock sensor connector and ECM connector.

NOTE: The harness between both connectors is shielded. Repair short circuit of harness together with shield.

3. CHECK INPUT SIGNAL FOR ECM.

Connect the connectors to ECM and knock sensor.
Turn the ignition switch to ON.
Measure the voltage between ECM and chassis ground.
Connector & terminal

(B136) 25 (+) - Chassis ground (-):

Is the voltage more than 2 V?

Even if malfunction indicator light lights up, the circuit has returned to a normal condition at this time. (However, the possibility of poor contact still remains.)

NOTE: In this case, repair the following:

Poor contact in knock sensor connector
Poor contact in ECM connector
Poor contact in coupling connector

Repair poor contact in ECM connector.