DTC P0325, P0326, P0327, or P0332. Buick Lucerne 2007

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2007 🢒 Lucerne 🢒 DTC 🢒 DTC P0325, P0326, P0327, or P0332

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0325: Knock Sensor (KS) Module Performance

DTC P0327: Knock Sensor (KS) Circuit Bank 1

DTC P0332: Knock Sensor (KS) Circuit Bank 2

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Knock Sensor Signal	P0327	P0325, P0327	P0325, P0327	P0325, P0327	P0325
Low Reference	P0327	P0327	P0327	P0325, P0327	P0325

Typical Scan Tool Data

Spark

Circuit	Normal Range	Short to Ground	Open	Short to Voltage
Knock Sensor/Spark	11-20	0-25	0-25	0-25

The Knock Sensor (KS) System enables the control module to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The sensors are located below each cylinder head on the engine block. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The control module adjusts the spark timing based on the amplitude and the frequency of the KS signal. The control module receives the KS signal through a signal circuit. The control module learns a minimum KS noise level at idle and uses calibrated values for the rest of the RPM range. The control module should monitor a normal KS signal within the noise channel. If the control module malfunctions in a manner that will not allow proper diagnosis of the KS system, DTC P0325 sets. If the control module detects the KS signal outside of the noise channel, or the KS signal is not present. DTC P0327 refers to the bank 1 KS and DTC P0332 refers to the bank 2 KS.

Conditions for Running the DTC

•	DTCs P0016, P0101, P0102, P0103, P0116, P0117, P0118, P0120, P0125-L32 only, P0128, P0220, P0335, P0336, P0340, P0341, P0608, P1125, P1516, P2101, P2108, P2120, P2125, P2135, or P2138 are not set.

•	The engine speed is between 1,000-5,000 RPM.

•	The throttle position (TP) indicated angle is more than 10 percent.

•	The engine load is more than 40 percent.

•	The engine coolant temperature (ECT) is more than 60°C (140°F).

•	The knock retard is less than 15 degrees.

•	The ignition 1 signal is more than 9 volts.

•	The engine run time is more than 30 seconds.

•	DTC P0325, P0327, and P0332 runs continuously when the above conditions are met.

Conditions for Setting the DTC

P0325

The control module detects a malfunction in the KS diagnostic circuitry that will not allow proper diagnosis of the KS system.

P0327 or P0332

The KS signal is outside of the assigned noise channel or the KS signal is not present for more than 0.5 second.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

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

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

•	The KS must be clear of hoses, brackets, and engine electrical wiring.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

•	Engine Controls Connector End Views

•	Powertrain Control Module Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Circuit/System Testing

Important:

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical .

Test for an intermittent and for a poor connection at the affected KS.
With the ignition OFF, disconnect the affected KS.
With the ignition OFF, measure for 93K -107K ohms from the sensor signal terminal on the KS to a good ground with a DMM.

⇒	If resistance does not measure within the specified values, replace the affected KS.

Important: DO NOT tap on plastic engine components.

Connect the DMM between the terminal of the affected KS. Set the DMM to the 400 Hz scale, let stabilize at 0 Hz. Tap on engine block with a non-metallic object near the affected KS while observing the signal indicated on the DMM.

⇒	If the DMM does not display a fluctuating frequency while tapping on the engine block then replace the affected KS.

Turn the ignition ON, engine OFF. Set the DMM to the DC voltage scale. Measure for 4.2 volts from the KS signal circuit to a good ground with the DMM.

⇒	If over 4.2 volts, turn the ignition OFF, disconnect the control module and test the KS signal circuit for a short to voltage.

⇒	If under 4.2 volts, turn the ignition OFF, disconnect the control module test the KS signal circuit for an open, short to ground, or high resistance.

Test for intermittent or poor connections at the control module .
If all circuits test normal, replace the control module .

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Knock Sensor 1 Replacement

•	Knock Sensor 2 Replacement

•	Control Module References for ECM replacement, setup, and programming