Spark

DTC P0325 or P0326 - FX3

The knock sensor system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The knock sensor produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the knock sensor signal. The ECM receives the knock sensor signal through a signal circuit and a low reference circuit. The ECM learns a minimum knock sensor noise level at idle and uses calibrated values for the rest of the RPM range. The ECM should monitor a normal knock sensor signal within the noise channel.

P0325

The ECM detects a failure in the knock sensor or an open on the knock sensor circuit.

P0326

The ECM detects a failure in the knock sensor or short circuit to battery or ground on the knock sensor circuit.

DTC P0325 and P0326 are Type C DTCs.

DTC P0325 and P0326 are Type C DTCs.

Schematic Reference

Engine Controls Schematics : Siemens ECM - LPG with LCP → Siemens ECM - Gas without FX3 or LCP → Delphi ECM - FX3

Connector End View Reference

Component Connector End Views

Description and Operation

Knock Sensor System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Engine running, observe the DTC information with a scan tool. DTC P0325 or P0326 should not set.
2. Observe the knock sensor circuit test status parameters. Each of the knock sensor circuit test status parameters should display OK or Not Run.
3. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Note: If the B68 knock sensor lead is damaged in any way, replace the B68 knock sensor.

1. Ignition OFF, inspect for the following:

•	Inspect the knock sensor for physical damage. A knock sensor that is dropped or damaged may cause a DTC to set

•	Inspect the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause a DTC to set. The knock sensor should be free of thread sealant. The knock sensor mounting surface should be free of burrs, casting flash, and foreign material

•	The knock sensor must be clear of hoses, brackets and engine electrical wiring

•	Inspect for loose accessory brackets

•	Inspect for serpentine belt and tensioner wear

•	Inspect for an engine mechanical condition-Refer to Symptoms - Engine Mechanical

⇒	If a condition is found, repair as necessary.

2. Ignition OFF, disconnect the harness connector at the B68 knock sensor.
3. Ignition ON, test for 1-3V between the low reference circuit terminal 2 and ground.

⇒	If less than the specified range, test the low reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.

⇒	If greater than the specified range, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.

4. Ignition ON, test for 1-3V between the signal circuit terminal 1 and ground.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.

5. If all circuits test normal, test or replace the B68 knock sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.