AutoCodes – GMC – P0131 2018 GMC Sierra

P0131 2018 GMC Sierra Code - HO2S Circuit Low Voltage Bank 1 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 (HO2S) Bank 1, Front Heated Oxygen Sensor Bank 1 harness is open or shorted, Front Heated Oxygen Sensor Bank 1 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: P0131 2018 GMC Sierra indicates HO2S Circuit Low Voltage Bank 1 Sensor 1.
Common causes: Common causes include Faulty Front Heated Oxygen Sensor (HO2S) Bank 1, Front Heated Oxygen Sensor Bank 1 harness is open or shorted, Front Heated Oxygen Sensor Bank 1 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 270

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 26, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0131 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 P0131 2018 GMC Sierra - HO2S Circuit Low Voltage Bank 1 Sensor 1 - AutoCodes.com — P0131 2018 GMC Sierra Code - HO2S Circuit Low Voltage Bank 1 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P0131 2018 GMC Sierra?

Faulty Front Heated Oxygen Sensor (HO2S) Bank 1
Front Heated Oxygen Sensor Bank 1 harness is open or shorted
Front Heated Oxygen Sensor Bank 1 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 P0131 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 1 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0131 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.

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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 P0131 2018 GMC Sierra Code

1. What does the OBDII code P0131 mean on a 2018 GMC Sierra?

P0131 indicates that the oxygen sensor (HO2S) in Bank 1 Sensor 1 is reporting a voltage lower than expected, often due to an issue in the sensor circuit.

2. What are the common symptoms of a P0131 code on a 2018 GMC Sierra?

Symptoms may include a check engine light, poor fuel economy, rough idling, lack of power, and increased exhaust emissions.

3. What causes the P0131 code on a GMC Sierra?

Possible causes include a faulty oxygen sensor, wiring issues in the sensor circuit, a vacuum leak, a malfunctioning fuel injector, or low fuel pressure.

4. Which oxygen sensor is Bank 1 Sensor 1 on a 2018 GMC Sierra?

Bank 1 Sensor 1 is the upstream oxygen sensor located before the catalytic converter on the side of the engine with cylinder 1.

5. Can a dirty air filter cause a P0131 code?

While unlikely, a severely clogged air filter may affect air-fuel mixture, which could indirectly contribute to sensor issues. However, it is not a common cause.

6. How can I diagnose a P0131 code on my 2018 GMC Sierra?

Use an OBDII scanner to confirm the code, inspect the oxygen sensor and its wiring, check for vacuum leaks, test fuel pressure, and examine the air-fuel mixture.

7. Can driving with a P0131 code damage my engine?

Driving for an extended period with a P0131 code can cause poor engine performance and potential damage to the catalytic converter due to improper air-fuel ratios.

8. How do I fix the P0131 code on a 2018 GMC Sierra?

Repairs may include replacing the oxygen sensor, repairing damaged wiring, fixing vacuum leaks, cleaning or replacing fuel injectors, or addressing fuel pressure issues.

9. How much does it cost to repair a P0131 code on a GMC Sierra?

The cost varies depending on the issue. Replacing an oxygen sensor typically costs $150â€“$300, while addressing wiring or fuel system issues may cost more.

10. Can a P0131 code clear itself on a 2018 GMC Sierra?

The code may temporarily clear if the condition causing it is intermittent, but permanent resolution requires addressing the underlying issue.