DTC P0325, P0326, P0327, or P0332. Buick Terraza

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2006 🢒 Terraza - 4WD 🢒 DTC 🢒 DTC P0325, P0326, P0327, or P0332

DTC Descriptors

DTC P0325: Knock Sensor (KS) Module Performance

DTC P0326: Knock Sensor (KS) Performance Bank 1

DTC P0327: Knock Sensor (KS) Circuit Bank 1

DTC P0332: Knock Sensor (KS) Circuit Bank 2

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Knock Sensor Signal	P0327, P0332	P0325, P0327, P0332	P0325, P0327, P0332	P0325, P0327, P0332	P0326
Low Reference	P0327, P0332	P0327, P0332	P0327, P0332	P0325, P0327, P0332	P0326

Circuit/System Description

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 2 isolated signal circuits. 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.

Conditions for Running the DTC

•	DTC P0016, P0101, P0102, P0103, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0220, P0222, P0223, P0335, P0336, P0340, P0341, P0608, P060D, P062F, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 is not set.

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

•	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, P0326, P0327 and P0332 run continuously once 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.

P0326

•	The KS indicates an excessive engine knock is present.

•	The control module commanded spark retard at a given engine load and speed 10 more than a calibrated value.

•	The above conditions exist for 5 seconds.

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.

•	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

•	Engine Control Module Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Circuit/System Testing

Turn OFF the ignition.
Disconnect the KS.
Measure for infinite resistance from the KS signal circuit on the sensor side of the KS harness connector to a good ground with the DMM.
Measure for infinite resistance from the KS low reference circuit on the sensor side of the KS harness connector to a good ground with the DMM.

⇒	If the circuits are grounded, repair the short to ground.

Turn ON the ignition, with the engine OFF.
On the control module side of the KS harness connector, measure the DC voltage from the KS signal circuit to a good ground with a DMM.
On the control module side of the KS harness connector, measure for 2.5 DC volts from the KS low reference circuit to a good ground with a DMM.

⇒	If the KS signal circuit or the KS low reference circuit measures more than the specified range, inspect for a short to voltage. If the circuit tests normal, replace the control module.

Test the KS signal circuit and the KS low reference circuit for the following conditions:

•

An open

•	A short to ground

•	High resistance

•	KS circuits shorted together

⇒	If the circuits and the sensor test normal, replace the control module.

Component Testing

Connect the DMM from the KS signal circuit to the KS low reference circuit on the sensor side of the KS harness connector.
Set the DMM to the 400 mV AC hertz scale and wait for the DMM to stabilize at 0 Hz.

Important: DO NOT tap on plastic engine components.

Tap on the engine block with a non-metallic object near the KS while observing the signal indicated on the DMM.
The DMM should display a fluctuating frequency while tapping on the engine block.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

•	Knock Sensor Replacement - Bank 1

•	Knock Sensor Replacement - Bank 2