AutoCodes – GMC – P0157 2017 GMC Sierra

P0157 2017 GMC Sierra Code - HO2S Circuit Low Voltage Bank 2 Sensor 2

Quick Answer

The Heated Oxygen Sensors (HO2S) are used for fuel control and catalyst monitoring. Common causes include Faulty Rear Heated Oxygen Sensor Bank 2, Rear Heated Oxygen Sensor Bank 2 harness is open or shorted, Rear 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: P0157 2017 GMC Sierra indicates HO2S Circuit Low Voltage Bank 2 Sensor 2.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 2, Rear Heated Oxygen Sensor Bank 2 harness is open or shorted, Rear 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 237

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0157 2017 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 P0157 2017 GMC Sierra - HO2S Circuit Low Voltage Bank 2 Sensor 2 - AutoCodes.com — P0157 2017 GMC Sierra Code - HO2S Circuit Low Voltage Bank 2 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0157 2017 GMC Sierra?

Faulty Rear Heated Oxygen Sensor Bank 2
Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
Rear 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 P0157 2017 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 Rear Heated Oxygen Sensor (HO2S) Bank 2 usually takes care of the problem.

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0157 2017 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 P0157 2017 GMC Sierra code?

Need more information on how to fix the P0157 2017 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0157 2017 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P0157 2017 GMC Sierra Code

What does OBD-II code P0157 mean for a 2017 GMC Sierra?

Code P0157 indicates that the voltage of the downstream oxygen sensor (Bank 2, Sensor 2) is lower than expected. This sensor monitors the efficiency of the catalytic converter.

What are the common symptoms of code P0157 in a 2017 GMC Sierra?

Common symptoms include the Check Engine Light turning on, reduced fuel efficiency, rough idle, and possibly increased emissions.

What causes code P0157 to appear on a 2017 GMC Sierra?

The code is often caused by a faulty oxygen sensor, exhaust leaks, damaged wiring, a failing catalytic converter, or engine running too rich or too lean.

Can a faulty oxygen sensor cause code P0157 in a 2017 GMC Sierra?

Yes, a defective Bank 2, Sensor 2 oxygen sensor is one of the most common causes of code P0157.

How do I diagnose code P0157 on a 2017 GMC Sierra?

Start by inspecting the Bank 2, Sensor 2 oxygen sensor and its wiring for damage, checking for exhaust leaks, and using a scan tool to monitor sensor voltage.

Is it safe to drive a 2017 GMC Sierra with code P0157?

Driving with code P0157 may not cause immediate damage, but prolonged driving can lead to poor fuel economy and increased emissions. Repairs should be made promptly.

How do I fix code P0157 on a 2017 GMC Sierra?

Repairs may involve replacing the Bank 2, Sensor 2 oxygen sensor, fixing exhaust leaks, repairing damaged wiring, or addressing issues with the catalytic converter.

Can poor fuel quality trigger code P0157 in a 2017 GMC Sierra?

While poor fuel quality is less likely to directly cause P0157, it can contribute to engine running conditions that may affect the oxygen sensor readings.

How much does it typically cost to repair code P0157 on a 2017 GMC Sierra?

Repair costs vary but typically range from $150 to $400, depending on whether the oxygen sensor needs replacement or other issues, such as wiring or exhaust leaks, need repair.

Do I need any special tools to fix code P0157 on a 2017 GMC Sierra?

You may need an OBD-II scanner to diagnose the code, a wrench to replace the oxygen sensor, and possibly tools to repair wiring or exhaust components.