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P11D2 2016 GMC Sierra Code - O2 Signal Circuit High 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
P11D2 2016 GMC Sierra indicates O2 Signal Circuit High 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 148
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 P11D2 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 P11D2 2016 GMC Sierra - O2 Signal Circuit High Voltage (NOx Sensor 2) - AutoCodes.com
P11D2 2016 GMC Sierra Code - O2 Signal Circuit High Voltage (NOx Sensor 2)
What does this mean?

What are the Possible Causes of the DTC P11D2 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 P11D2 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 P11D2 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 P11D2 2016 GMC Sierra code?

Need more information on how to fix the P11D2 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11D2 2016 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P11D2 2016 GMC Sierra Code

1. What does the OBDII code P11D2 mean on a 2016 GMC Sierra?

P11D2 indicates a high voltage issue in the O2 signal circuit of NOx Sensor 2, which monitors nitrogen oxides in the exhaust system.

2. What are the common symptoms of a P11D2 code?

Symptoms may include reduced fuel efficiency, an illuminated check engine light, diminished engine performance, or the vehicle entering limp mode.

3. What causes the P11D2 code to appear?

Common causes include a damaged NOx sensor 2, wiring issues like frayed or corroded connections, or a malfunctioning engine control module (ECM).

4. Can I drive my 2016 GMC Sierra with a P11D2 code?

While you may be able to drive, it’s not recommended as it could lead to increased emissions, poor performance, or further damage to the emission control system.

5. How is the P11D2 code diagnosed?

A technician will inspect the NOx sensor, check for wiring or connector damage, and use a scan tool to monitor live data from the sensor to confirm the issue.

6. How do you fix the P11D2 code on a 2016 GMC Sierra?

Repairs may include replacing the NOx sensor 2, repairing damaged wiring or connectors, and clearing the code with a scan tool.

7. How much does it cost to fix the P11D2 code?

The cost varies but typically ranges from $300 to $800, depending on whether the NOx sensor or wiring needs repair or replacement.

8. Can a dirty exhaust system cause a P11D2 code?

Yes, excessive soot or contamination in the exhaust system can interfere with the NOx sensor's performance, potentially triggering the code.

9. What tools are needed to troubleshoot the P11D2 code?

You’ll need an OBDII scanner, a multimeter to check voltage and continuity, and possibly tools to access and inspect the NOx sensor and wiring.

10. Will clearing the P11D2 code with a scan tool fix the issue?

Clearing the code may temporarily turn off the check engine light, but the underlying issue must be resolved to prevent the code from returning.

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