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P11BF Chevrolet 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 Chevrolet 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 396

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P11BF Chevrolet 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 Chevrolet - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11BF Chevrolet Code - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11BF Chevrolet?

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 Chevrolet?

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 Chevrolet 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.

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Information for Specific Chevrolet Models

P11BF 2014 Chevrolet Silverado — O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)
P11BF 2015 Chevrolet Silverado — O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)
P11BF 2016 Chevrolet Silverado — O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)
P11BF 2017 Chevrolet Silverado — O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)
P11BF 2018 Chevrolet Silverado — O2 Reference Voltage Circuit Low Voltage (NOx Sensor 2)

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 Chevrolet Code

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

P11BF indicates a low voltage issue in the O2 reference voltage circuit for NOx Sensor 2, which may affect the sensor's ability to monitor nitrogen oxide levels properly.

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

Symptoms may include an illuminated check engine light, reduced fuel efficiency, poor engine performance, and potential issues with emissions compliance.

3. What causes the P11BF code on a Chevrolet?

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

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

Yes, a malfunctioning NOx Sensor 2 can fail to generate the required reference voltage, triggering the P11BF code.

5. How can I troubleshoot the P11BF code?

Start by inspecting the wiring and connectors for damage or corrosion. Use a multimeter to check for proper voltage and continuity in the circuit. If no issues are found, test or replace the NOx Sensor 2.

6. Is it safe to drive with the P11BF code?

Driving with this code is not recommended as it may lead to higher emissions, reduced fuel efficiency, and potential damage to the catalytic converter over time.

7. How much does it cost to repair the P11BF code?

Repairs can range from $200 to $700 depending on whether you need to replace the NOx sensor, fix wiring issues, or address other related problems.

8. Can a dirty sensor cause the P11BF code?

While contamination can impact sensor performance, the P11BF code specifically points to a low voltage issue, which is more likely caused by electrical faults or sensor failure.

9. How do I reset the P11BF code after repairs?

Use an OBDII scanner to clear the code after addressing the issue. If the problem is resolved, the code should not return.

10. Does the P11BF code affect emissions testing?

Yes, the P11BF code can cause your vehicle to fail an emissions test since the NOx sensor plays a critical role in monitoring and controlling exhaust emissions.