AutoCodes – GMC – P0151 2018 GMC Sierra

P0151 2018 GMC Sierra Code - HO2S Circuit Low Voltage Bank 2 Sensor 1

Quick Answer

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Common causes include Faulty Front Heated Oxygen Sensor Bank 2, Front Heated Oxygen Sensor Bank 2 harness is open or shorted, Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection. 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: P0151 2018 GMC Sierra indicates HO2S Circuit Low Voltage Bank 2 Sensor 1.
Common causes: Common causes include Faulty Front Heated Oxygen Sensor Bank 2, Front Heated Oxygen Sensor Bank 2 harness is open or shorted, Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection.
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 284

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 May 27, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0151 2018 GMC Sierra Description

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the Engine Control Module (ECM) operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0 - 1, 000 mV. Once sufficient HO2S voltage fluctuation is observed by the ECM, Closed Loop is entered. The ECM uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases toward 1, 000 mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the ECM to calculate the air-to-fuel ratio sooner.
The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the heated oxygen sensor is shorted to ground if the HO2S voltage is less than 50 mV.

OBDII Code P0151 2018 GMC Sierra - HO2S Circuit Low Voltage Bank 2 Sensor 1 - AutoCodes.com — P0151 2018 GMC Sierra Code - HO2S Circuit Low Voltage Bank 2 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P0151 2018 GMC Sierra?

Faulty Front Heated Oxygen Sensor Bank 2
Front Heated Oxygen Sensor Bank 2 harness is open or shorted
Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection
Low or high fuel system pressure
Fuel contamination
Faulty fuel injectors
Exhaust gas leaks
Engine vacuum leaks

How to Fix the DTC P0151 2018 GMC Sierra?

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

Replacing the Front Heated Oxygen Sensor (HO2S) Bank 2 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0151 2018 GMC Sierra 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 P0151 2018 GMC Sierra code?

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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 P0151 2018 GMC Sierra Code

What does the OBDII code P0151 mean for a 2018 GMC Sierra?

P0151 indicates that the oxygen sensor (HO2S) for Bank 2 Sensor 1 is reporting a consistently low voltage, meaning the air-fuel mixture is likely too lean.

What are the common symptoms of code P0151 in a 2018 GMC Sierra?

Symptoms may include a check engine light, poor fuel economy, rough idling, reduced engine performance, or hesitation during acceleration.

What causes the P0151 code to appear on a 2018 GMC Sierra?

Possible causes include a faulty oxygen sensor, damaged wiring or connectors, exhaust leaks near the sensor, or a vacuum leak causing a lean condition.

How do I locate Bank 2 Sensor 1 on a 2018 GMC Sierra?

Bank 2 refers to the side of the engine opposite the #1 cylinder, and Sensor 1 is the oxygen sensor located before the catalytic converter on that side.

Can I drive my 2018 GMC Sierra with a P0151 code?

While the vehicle may still be drivable, ignoring the code can lead to poor performance, increased emissions, and potential damage to other components like the catalytic converter.

How do I fix the P0151 code on a 2018 GMC Sierra?

Repairs may include replacing the faulty oxygen sensor, repairing damaged wiring or connectors, fixing exhaust or vacuum leaks, or addressing issues with the engine control unit.

How do I test the oxygen sensor for a P0151 code?

Use a multimeter or scan tool to check the sensor’s voltage and response time. A consistently low voltage reading may indicate a faulty sensor.

Can a dirty MAF sensor cause the P0151 code on a 2018 GMC Sierra?

Yes, a dirty or malfunctioning mass airflow (MAF) sensor can cause a lean condition, which may lead to the P0151 code being triggered.

Does bad fuel quality contribute to the P0151 code?

Poor fuel quality can cause an improper air-fuel ratio, potentially triggering the P0151 code if the mixture is too lean.

Will clearing the code fix the P0151 issue on my 2018 GMC Sierra?

Clearing the code may temporarily turn off the check engine light, but it won’t resolve the underlying problem. Proper diagnosis and repair are necessary.