AutoCodes – GMC – P0327 GMC

P0327 GMC Code - Knock Sensor Circuit Low Voltage Bank 1

Quick Answer

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, also known as spark knock. Common causes include Faulty Knock Sensor Bank 1, Knock Sensor Bank 1 circuit poor electrical connection, Knock Sensor Bank 1 harness is open or shorted. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0327 GMC indicates Knock Sensor Circuit Low Voltage Bank 1.
Common causes: Common causes include Faulty Knock Sensor Bank 1, Knock Sensor Bank 1 circuit poor electrical connection, Knock Sensor Bank 1 harness is open or shorted.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 16,667

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 13, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0327 GMC Description

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, also known as spark knock. The knock sensor system uses one or two flat response 2-wire sensors. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The amplitude and frequency are dependent upon the level of knock that the knock sensor detects. The ECM receives the knock sensor signal through two isolated signal circuits for each knock sensor.
The control module learns a minimum noise level, or background noise, at idle from the knock sensor and uses calibrated values for the rest of the RPM range. The control module uses the minimum noise level to calculate a noise channel. A normal knock sensor signal will ride within the noise channel. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the normal knock sensor signal, keeping the signal within the channel. In order to determine which cylinders are knocking, the control module only uses knock sensor signal information when each cylinder is near the Top Dead Center (TDC) of the firing stroke. If a knock is present, the signal will range outside of the noise channel.
If the control module has determined that a knock is present, it will retard the ignition timing to attempt to eliminate the knock. The control module will always try to work back to a zero-compensation level, or no spark retard. An abnormal knock sensor signal will stay outside of the noise channel or will not be present. knock sensor diagnostics are calibrated to detect faults with the knock sensor circuitry inside the control module, the knock sensor wiring, or the knock sensor voltage output. Some diagnostics are also calibrated to detect constant noise from an outside influence such as a loose/damaged component or excessive engine mechanical noise.
The Diagnostic Trouble Code (DTC) will be set when the signal from the Knock Sensor Bank 1 is short to ground for greater than 5s.

OBDII Code P0327 GMC - Knock Sensor Circuit Low Voltage Bank 1 - AutoCodes.com — P0327 GMC Code - Knock Sensor Circuit Low Voltage Bank 1

What does this mean?

What are the Possible Causes of the DTC P0327 GMC?

Faulty Knock Sensor Bank 1
Knock Sensor Bank 1 circuit poor electrical connection
Knock Sensor Bank 1 harness is open or shorted
Faulty Engine Control Module (ECM)

How to Fix the DTC P0327 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The P0327 code means that the Knock Sensor is not working properly. Problems with the knock sensor will not cause engine performance problems. Replacing the knock sensor usually takes care of the problem.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0327 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific GMC Models

P0327 2014 GMC Sierra — Knock Sensor Circuit Low Voltage Bank 1
P0327 2015 GMC Sierra — Knock Sensor Circuit Low Voltage Bank 1
P0327 2016 GMC Sierra — Knock Sensor Circuit Low Voltage Bank 1
P0327 2017 GMC Sierra — Knock Sensor Circuit Low Voltage Bank 1
P0327 2018 GMC Sierra — Knock Sensor Circuit Low Voltage Bank 1

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0327 GMC Code

What does the OBDII code P0327 mean on a GMC vehicle?

P0327 indicates that the Knock Sensor Circuit on Bank 1 is detecting a low voltage signal, which can affect the engine's ability to detect and adjust for knocking.

What are the common symptoms of code P0327 in a GMC?

Symptoms can include poor engine performance, reduced fuel efficiency, illuminated check engine light, and in some cases, engine knocking or pinging.

What causes the P0327 code to appear on my GMC?

Common causes include a faulty knock sensor, damaged wiring or connectors in the knock sensor circuit, an engine control module (ECM) issue, or excessive engine vibrations.

Can I drive my GMC with a P0327 code?

You may be able to drive with this code, but it is not recommended. Ignoring it can lead to engine damage due to undetected knocking or pinging.

How can I diagnose the P0327 code on my GMC?

Inspect the wiring and connectors around the knock sensor for damage or corrosion, test the knock sensor for proper operation, and check for any related engine issues that may cause abnormal vibrations.

What tools do I need to fix a P0327 code on my GMC?

You’ll typically need an OBDII scanner, multimeter, and basic tools for inspecting and replacing the knock sensor or repairing damaged wiring.

How much does it cost to fix a P0327 code on a GMC?

Repair costs can vary, but replacing a knock sensor typically costs between $150 and $400, including parts and labor, depending on your vehicle model.

Where is the knock sensor located on my GMC?

The knock sensor is usually located on the engine block, cylinder head, or intake manifold, depending on the specific model and engine configuration.

Can a bad knock sensor cause long-term damage to my GMC?

Yes, a faulty knock sensor can prevent the engine from detecting and adjusting for knocking, potentially leading to engine damage over time.

How do I prevent the P0327 code from recurring on my GMC?

Ensure proper maintenance of the vehicle, including checking for damaged wiring, keeping the engine in good condition, and using the correct fuel grade recommended by the manufacturer.