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P11FD 2016 GMC Sierra 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 2016 GMC Sierra 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 164

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 P11FD 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 P11FD 2016 GMC Sierra - O2 Low Reference Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11FD 2016 GMC Sierra Code - O2 Low Reference Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11FD 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 P11FD 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 P11FD 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 P11FD 2016 GMC Sierra 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 2016 GMC Sierra Code

What does the OBDII code P11FD mean for a 2016 GMC Sierra?

The P11FD code indicates a low voltage issue in the O2 low reference circuit related to the NOx sensor 2, which affects the vehicle's emissions control system.

What are common symptoms of the P11FD code?

Common symptoms include the check engine light being illuminated, poor engine performance, increased emissions, and potential issues with fuel efficiency.

What could cause the P11FD code to trigger?

Possible causes include a faulty NOx sensor 2, damaged wiring or connectors in the O2 low reference circuit, or issues with the engine control module (ECM).

How can I diagnose the P11FD code?

To diagnose the P11FD code, use an OBDII scanner to confirm the code, inspect the NOx sensor and associated wiring for damage, and check the voltage levels in the O2 low reference circuit.

What are some repair options for the P11FD code?

Repair options may include replacing the NOx sensor 2, repairing or replacing damaged wiring or connectors, and ensuring the ECM is functioning properly.

Can I drive my 2016 GMC Sierra with the P11FD code?

While it may be possible to drive the vehicle, it's not recommended as it can lead to increased emissions and potential damage to the engine or exhaust system.

How much does it typically cost to fix the P11FD code?

Repair costs can vary widely, but expect to pay anywhere from $100 to $500 depending on whether you need to replace the NOx sensor or repair wiring issues.

Is the P11FD code related to other codes?

Yes, the P11FD code can be related to other codes associated with the NOx sensor or emissions system, so it's important to check for additional codes when diagnosing.

What should I do if I clear the P11FD code and it comes back?

If you clear the code and it returns, further diagnosis is needed to identify the underlying issue, which may include checking the sensor's functionality and inspecting the wiring again.