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P11FD 2014 Chevrolet Silverado Code - O2 Low Reference 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
P11FD 2014 Chevrolet Silverado indicates O2 Low Reference 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 283
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 P11FD 2014 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 P11FD 2014 Chevrolet Silverado - O2 Low Reference Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com
P11FD 2014 Chevrolet Silverado Code - O2 Low Reference Circuit Low Voltage (NOx Sensor 2)
What does this mean?

What are the Possible Causes of the DTC P11FD 2014 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 P11FD 2014 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 P11FD 2014 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 P11FD 2014 Chevrolet Silverado code?

Need more information on how to fix the P11FD 2014 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 P11FD 2014 Chevrolet Silverado Code

What does OBDII code P11FD mean for a 2014 Chevrolet Silverado?

Code P11FD indicates a problem with the low reference circuit for NOx Sensor 2, specifically detecting low voltage.

What are the common symptoms of code P11FD in a 2014 Chevrolet Silverado?

Symptoms may include a check engine light, reduced fuel efficiency, rough idling, and potential engine performance issues.

What causes the P11FD code in a Chevrolet Silverado?

Common causes include a faulty NOx Sensor 2, damaged wiring or connectors in the low reference circuit, or a malfunction in the Engine Control Module (ECM).

Can I drive my 2014 Silverado with the P11FD code?

While driving with this code may not immediately damage the engine, it can impair fuel efficiency and emissions performance, so repairs should be prioritized.

How do I diagnose the P11FD code?

Start by inspecting the wiring and connectors around NOx Sensor 2 for damage or corrosion. Use a multimeter to test the sensor circuit and confirm voltage levels.

Can a faulty NOx Sensor 2 trigger the P11FD code?

Yes, a defective NOx Sensor 2 is a common cause of this code and may require replacement.

How much does it cost to fix the P11FD code on a 2014 Silverado?

Repair costs vary but typically range from $200 to $600, depending on whether the issue is with the sensor, wiring, or ECM.

Can a bad ECM cause the P11FD code?

While less common, a malfunctioning ECM can cause the P11FD code if it fails to properly interpret or regulate the NOx sensor signals.

What tools are needed to troubleshoot the P11FD code?

You’ll need an OBDII scanner, a multimeter to check electrical signals, and possibly a wiring diagram for the NOx sensor circuit.

How do I prevent the P11FD code from occurring again?

Regularly inspect and maintain the NOx sensors, wiring, and connectors. Address any exhaust system issues promptly to avoid sensor damage.

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