AutoCodes.com
Login with Google
AutoCodes – GMC – P11BF 2018 GMC Sierra

P11BF 2018 GMC Sierra Code - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)

Quick Answer

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. Common causes include Faulty Nitrogen Oxides (NOx) Sensor 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides 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
P11BF 2018 GMC Sierra indicates O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2).
Common causes
Common causes include Faulty Nitrogen Oxides (NOx) Sensor 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides 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.
Save to My Repairs My Repairs
AI answers can be wrong. Verify repairs with testing. Open full chat
Code Popularity 181
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 24, 2024
💬 Need more help? Ask Coddy for instant answers — it's free!

Code P11BF 2018 GMC Sierra Description

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 Engine Control Module (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 if the ECM software detects a fault in the NOx sensor circuitry or a performance fault in the NOx sensor for greater than 2 s.
OBDII Code P11BF 2018 GMC Sierra - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com
P11BF 2018 GMC Sierra Code - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)
What does this mean?

What are the Possible Causes of the DTC P11BF 2018 GMC Sierra?

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

How to Fix the DTC P11BF 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 P11BF 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 P11BF 2018 GMC Sierra code?

Need more information on how to fix the P11BF 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11BF 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 P11BF 2018 GMC Sierra Code

1. What does the OBDII code P11BF mean on a 2018 GMC Sierra?

P11BF indicates an "O2 Reference Voltage Circuit Low Voltage" issue related to NOx Sensor 2, which monitors nitrogen oxide levels in the exhaust system.

2. What are the symptoms of the P11BF code on a 2018 GMC Sierra?

Common symptoms include a check engine light, reduced fuel efficiency, poor engine performance, and potential entry into limp mode.

3. What causes the P11BF code to appear?

Causes can include a faulty NOx sensor, damaged sensor wiring, poor electrical connections, or an issue with the powertrain control module (PCM).

4. Can I drive my 2018 GMC Sierra with the P11BF code?

While the vehicle may still be drivable, it’s recommended to address the issue promptly to avoid further damage to the emissions system or reduced engine performance.

5. How do I fix the P11BF code on my 2018 GMC Sierra?

Repairs may involve replacing the NOx sensor 2, repairing damaged wiring, cleaning electrical connections, or reprogramming/updating the PCM if necessary.

6. How can I diagnose the P11BF code on my GMC Sierra?

Diagnosis involves using an OBDII scanner to confirm the code, inspecting the NOx sensor and its wiring for damage, and testing the sensor's voltage and circuit continuity.

7. Is the P11BF code covered under warranty for a 2018 GMC Sierra?

It may be covered under the emissions warranty, depending on the vehicle’s mileage and warranty terms. Check with your dealership for details.

8. How much does it cost to repair the P11BF code on a 2018 GMC Sierra?

The cost can vary, but replacing a NOx sensor typically ranges from $300 to $700, including parts and labor, depending on the repair shop or dealership.

9. What happens if I ignore the P11BF code?

Ignoring it can lead to decreased fuel efficiency, higher emissions, potential damage to other components, and the vehicle failing an emissions test.

10. Can a software update fix the P11BF code on a 2018 GMC Sierra?

In some cases, a PCM software update or reprogramming may resolve the issue if the problem is related to incorrect sensor calibration.

Discuss the causes and fixes for P11BF 2018 GMC Sierra OBDII Code

Submit a New Comment

Code P11BF 2018 GMC Sierra comments

No comments found for this page.

AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play