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AutoCodes – GMC – P11B3 2018 GMC Sierra

P11B3 2018 GMC Sierra Code - HO2S Performance During Deceleration Fuel Cut-Off Bank 1 Sensor 2

Quick Answer

The oxygen content of the exhaust is measured via the nitrogen oxide (NOx) sensors. Common causes include Faulty Nitrogen Oxide (NOx) Sensor 2, Nitrogen Oxide Sensor 2 harness is open or shorted, Nitrogen Oxide Sensor 2 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P11B3 2018 GMC Sierra indicates HO2S Performance During Deceleration Fuel Cut-Off Bank 1 Sensor 2.
Common causes
Common causes include Faulty Nitrogen Oxide (NOx) Sensor 2, Nitrogen Oxide Sensor 2 harness is open or shorted, Nitrogen Oxide Sensor 2 circuit poor electrical connection.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code Popularity 214
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Sep 30, 2022
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Code P11B3 2018 GMC Sierra Description

The oxygen content of the exhaust is measured via the nitrogen oxide (NOx) sensors. The nitrogen oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. There are two NOx sensors, one placed upstream of selective catalytic reduction, to measure inlet NOx concentration, and one placed downstream. They are connected with the control module via CAN and all the information is exchanged through it. Since it is a smart sensor, all the electrical monitoring is performed inside the sensor and only the results are sent to the ECM. Each NOx sensor contains a sensing cell, a pumping cell, and a heater. A sample of exhaust gas passes through a diffusion gap between the sensing cell and the pumping cell. The NOx sensor maintains a constant reference voltage across the sensing cell. An electronic circuit within the sensor controls the pump current through the pumping cell in order to maintain a constant voltage in the sensing cell. The amount of current required to maintain the reference voltage in the sensing cell is proportional to the concentration of NOx in the exhaust. The ECM varies the amount of diesel exhaust fluid (reductant) added by varying the reductant injector duty cycle in response to changes in engine exhaust NOx levels. The smart NOx sensors consist of two components, the NOx module, and the NOx sensor element, that are serviced as a unit. A circuit or performance condition with a NOx sensor is detected by the NOx sensor module. The smart NOx sensor module communicates the condition to the ECM over the serial data line. The ECM sets a DTC when a serial data message is received from the NOx sensor module. The Diagnostic Trouble Code (DTC) will be set when the NOx sensor module detects a fault in the NOx sensor circuitry or a performance fault in the NOx sensor.
OBDII Code P11B3 2018 GMC Sierra - HO2S Performance During Deceleration Fuel Cut-Off Bank 1 Sensor 2 - AutoCodes.com
P11B3 2018 GMC Sierra Code - HO2S Performance During Deceleration Fuel Cut-Off Bank 1 Sensor 2
What does this mean?

What are the Possible Causes of the DTC P11B3 2018 GMC Sierra?

  • Faulty Nitrogen Oxide (NOx) Sensor 2
  • Nitrogen Oxide Sensor 2 harness is open or shorted
  • Nitrogen Oxide Sensor 2 circuit poor electrical connection

How to Fix the DTC P11B3 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P11B3 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 P11B3 2018 GMC Sierra code?

Need more information on how to fix the P11B3 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11B3 2018 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 P11B3 2018 GMC Sierra Code

1. What does the OBDII code P11B3 mean for a 2018 GMC Sierra?

P11B3 indicates an issue with the Bank 1 Sensor 2 (rear oxygen sensor) performance during deceleration fuel cut-off, meaning the sensor isn't responding as expected under specific conditions.

2. What are the common symptoms of code P11B3 in a 2018 GMC Sierra?

Symptoms may include an illuminated check engine light, reduced fuel efficiency, irregular exhaust readings, and possible rough idling or hesitation during deceleration.

3. What causes the P11B3 code to appear on a 2018 GMC Sierra?

Common causes include a faulty Bank 1 Sensor 2 oxygen sensor, exhaust leaks near the sensor, wiring issues, or a malfunction in the engine control module (ECM).

4. Can a faulty oxygen sensor trigger the P11B3 code in a 2018 GMC Sierra?

Yes, a failing or damaged Bank 1 Sensor 2 oxygen sensor is one of the primary reasons for this code.

5. How can I diagnose the P11B3 code on my 2018 GMC Sierra?

Use an OBDII scanner to confirm the code, inspect the wiring and connectors for damage, check for exhaust leaks, and test the oxygen sensor’s performance.

6. Is it safe to drive my 2018 GMC Sierra with the P11B3 code?

While the vehicle may still be drivable, ignoring the code can lead to increased emissions, reduced fuel efficiency, and potential damage to other components over time.

7. How do I fix the P11B3 code on a 2018 GMC Sierra?

Repairs may include replacing the Bank 1 Sensor 2 oxygen sensor, fixing exhaust leaks, repairing damaged wiring, or updating/reprogramming the ECM.

8. How much does it cost to repair the P11B3 code on a 2018 GMC Sierra?

Repair costs vary depending on the issue, but replacing an oxygen sensor typically costs between $150 and $300, while wiring or ECM repairs may be more.

9. Can an exhaust leak cause the P11B3 code on a 2018 GMC Sierra?

Yes, an exhaust leak near Bank 1 Sensor 2 can disrupt sensor readings and trigger the code.

10. Do I need to reset the ECM after fixing the P11B3 code on a 2018 GMC Sierra?

Yes, after repairs, clearing the code with an OBDII scanner is necessary to ensure the ECM recognizes the fix and monitors performance accurately.

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