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P11BF 2017 Chevrolet Silverado 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 2017 Chevrolet Silverado 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 259
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 2017 Chevrolet Silverado 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 2017 Chevrolet Silverado - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com
P11BF 2017 Chevrolet Silverado Code - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)
What does this mean?

What are the Possible Causes of the DTC P11BF 2017 Chevrolet Silverado?

  • 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 2017 Chevrolet Silverado?

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 2017 Chevrolet Silverado 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 2017 Chevrolet Silverado code?

Need more information on how to fix the P11BF 2017 Chevrolet Silverado 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 2017 Chevrolet Silverado Code

1. What does the OBDII code P11BF mean on a 2017 Chevrolet Silverado?

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 common symptoms of the P11BF code in a 2017 Chevy Silverado?

Symptoms may include a check engine light, reduced fuel efficiency, diminished engine performance, and the vehicle entering limp mode.

3. What causes the P11BF code to appear?

Common causes include a faulty NOx Sensor 2, damaged wiring or connectors in the O2 reference voltage circuit, or a malfunctioning engine control module (ECM).

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

Yes, a bad or failing NOx Sensor 2 is one of the primary causes of the P11BF code.

5. How do you diagnose the P11BF code on a 2017 Silverado?

Diagnosis includes scanning for codes with an OBDII reader, inspecting the NOx Sensor 2 wiring and connectors for damage, and testing the voltage in the O2 reference circuit.

6. Can I drive my Silverado with the P11BF code?

While the vehicle might still run, driving with this code can cause further damage to the emissions system and reduce engine efficiency. It's best to address the issue promptly.

7. How is the P11BF code typically fixed?

Repairs may involve replacing the NOx Sensor 2, repairing damaged wiring or connectors, or reprogramming the ECM if necessary.

8. How much does it cost to fix the P11BF code?

Repair costs depend on the root cause but may range from $300 to $1,000, with NOx sensor replacement being one of the more expensive fixes.

9. Can a software update fix the P11BF code?

In some cases, a software update to the ECM may resolve the issue if it's related to a programming error.

10. Is the P11BF code covered under warranty for a 2017 Chevrolet Silverado?

If your vehicle is still under the emissions warranty, the repair may be covered. Check with your dealership for details.

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