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P11BF 2016 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 2016 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.
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Code Popularity 161
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
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Code P11BF 2016 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 2016 GMC Sierra - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com
P11BF 2016 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 2016 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 2016 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 2016 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 2016 GMC Sierra code?

Need more information on how to fix the P11BF 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the 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 P11BF 2016 GMC Sierra Code

1. What does the OBDII code P11BF mean on a 2016 GMC Sierra?

P11BF indicates a low voltage issue in the O2 Reference Voltage Circuit for NOx Sensor 2, which monitors nitrogen oxide emissions.

2. What are the common symptoms of the P11BF code?

Common symptoms include the check engine light turning on, reduced engine performance, increased fuel consumption, and possible emissions test failure.

3. What causes the P11BF code to appear?

Potential causes include a faulty NOx sensor, damaged wiring or connectors in the O2 reference voltage circuit, or a malfunctioning Engine Control Module (ECM).

4. Can I drive my 2016 GMC Sierra with a P11BF code?

While it may still be drivable, driving with this code can lead to reduced performance, increased emissions, and possible damage to the catalytic converter if not addressed.

5. How do I diagnose the P11BF code?

Start by inspecting the wiring and connectors for damage or corrosion, then test the NOx sensor's voltage and resistance. If the issue persists, the ECM may need to be tested.

6. How is the P11BF code fixed?

Repairs may include replacing the NOx sensor, repairing or replacing damaged wiring, cleaning corroded connectors, or reprogramming or replacing the ECM.

7. How much does it cost to fix the P11BF code on a 2016 GMC Sierra?

Repair costs can range from $200 to $800, depending on whether the issue is with the NOx sensor, wiring, or ECM.

8. Is the P11BF code related to emissions?

Yes, the code is directly related to emissions since it involves the NOx sensor, which monitors and helps control nitrogen oxide levels.

9. Can a bad NOx sensor cause the P11BF code?

Yes, a faulty NOx sensor is one of the most common causes of the P11BF code.

10. Do I need to clear the P11BF code after repairs?

Yes, use an OBDII scanner to clear the code after repairs. If the issue is resolved, the code should not return.

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