AutoCodes – GMC – P0333 GMC

P0333 GMC Code - Knock Sensor Circuit High Voltage Bank 2

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 2, Knock Sensor Bank 2 circuit poor electrical connection, Knock Sensor Bank 2 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: P0333 GMC indicates Knock Sensor Circuit High Voltage Bank 2.
Common causes: Common causes include Faulty Knock Sensor Bank 2, Knock Sensor Bank 2 circuit poor electrical connection, Knock Sensor Bank 2 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 953

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
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0333 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 voltage for greater than 5s.

OBDII Code P0333 GMC - Knock Sensor Circuit High Voltage Bank 2 - AutoCodes.com — P0333 GMC Code - Knock Sensor Circuit High Voltage Bank 2

What does this mean?

What are the Possible Causes of the DTC P0333 GMC?

Faulty Knock Sensor Bank 2
Knock Sensor Bank 2 circuit poor electrical connection
Knock Sensor Bank 2 harness is open or shorted
Faulty Engine Control Module (ECM)

How to Fix the DTC P0333 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 P0333 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.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0333 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.

Need more information about the P0333 GMC code?

Need more information on how to fix the P0333 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0333 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P0333 2014 GMC Sierra — Knock Sensor Circuit High Voltage Bank 2
P0333 2015 GMC Sierra — Knock Sensor Circuit High Voltage Bank 2
P0333 2016 GMC Sierra — Knock Sensor Circuit High Voltage Bank 2
P0333 2017 GMC Sierra — Knock Sensor Circuit High Voltage Bank 2
P0333 2018 GMC Sierra — Knock Sensor Circuit High Voltage Bank 2

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 P0333 GMC Code

What does the OBDII code P0333 on a GMC mean?

P0333 indicates a high voltage condition in the knock sensor circuit on Bank 2, which monitors engine vibrations caused by detonation or pre-ignition.

What are common symptoms of the P0333 code?

Symptoms include engine knocking or pinging, reduced fuel efficiency, poor acceleration, and possibly an illuminated check engine light.

What causes the P0333 code on a GMC?

Common causes include a faulty knock sensor, damaged sensor wiring or connectors, issues with the engine control module (ECM), or excessive engine noise.

Can a bad knock sensor cause engine damage?

Yes, if the knock sensor fails to detect detonation, prolonged pre-ignition can lead to severe engine damage over time.

How is the P0333 code diagnosed?

Technicians typically use a scan tool to check for stored codes, inspect the knock sensor and wiring for damage, and test the sensorâ€™s voltage output.

Can I drive my GMC with the P0333 code?

Driving with the P0333 code may be possible, but itâ€™s not recommended due to potential engine damage from undetected knocking or inefficient performance.

How can I fix the P0333 code on my GMC?

Repairs may include replacing the faulty knock sensor, repairing or replacing damaged wiring, or reprogramming the ECM if necessary.

Where is the knock sensor located on a GMC vehicle?

The knock sensor is typically located on the engine block, cylinder head, or intake manifold, depending on the specific GMC model.

Will replacing the knock sensor clear the P0333 code?

Replacing the knock sensor may resolve the issue, but itâ€™s important to check the wiring and connectors to ensure the problem doesnâ€™t persist.

What tools are needed to fix the P0333 code?

Basic tools include a multimeter for testing voltage, a socket set for sensor removal, and possibly a scan tool to clear the fault code after repairs.