AutoCodes – GMC – P11D2 GMC

P11D2 GMC 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 GMC 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 321

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 P11D2 GMC 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 GMC - O2 Signal Circuit High Voltage (NOx Sensor 2) - AutoCodes.com — P11D2 GMC Code - O2 Signal Circuit High Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D2 GMC?

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 GMC?

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 GMC 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 GMC code?

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Information for Specific GMC Models

P11D2 2014 GMC Sierra — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 2015 GMC Sierra — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 2016 GMC Sierra — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 2017 GMC Sierra — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 2018 GMC Sierra — O2 Signal Circuit High 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 P11D2 GMC Code

1. What are the common symptoms of OBDII code P11D2 GMC (O2 Signal Circuit High Voltage - NOx Sensor 2)?

- Common symptoms include poor engine performance, reduced fuel efficiency, rough idle, and the illumination of the Check Engine Light.

2. What are the possible causes of OBDII code P11D2 GMC?

- Possible causes include a faulty NOx sensor, wiring issues in the O2 signal circuit, ECM (Engine Control Module) problems, or exhaust system leaks.

3. How can I diagnose OBDII code P11D2 GMC?

- Diagnosis typically involves using an OBDII scanner to read the code, checking the NOx sensor and related wiring for damage, and testing the sensor's voltage output.

4. Can I drive my vehicle with OBDII code P11D2 GMC active?

- It is generally not recommended to drive with this code active, as it can lead to further damage to the engine and emissions control system.

5. How can I repair OBDII code P11D2 GMC?

- Repair options include replacing the faulty NOx sensor, repairing or replacing damaged wiring, resetting the ECM, and fixing any exhaust leaks.

6. Will resetting the Check Engine Light fix OBDII code P11D2 GMC?

- Resetting the Check Engine Light may temporarily turn it off, but the underlying issue causing the code will still need to be addressed to prevent it from reoccurring.

7. Are there any DIY repair tips for OBDII code P11D2 GMC?

- DIY repair tips include checking the sensor wiring for visible damage, ensuring proper sensor connections, and using a multimeter to test voltage output.

8. How much does it cost to fix OBDII code P11D2 GMC at a repair shop?

- Repair costs can vary depending on the exact cause of the code, but expect to pay anywhere from $200 to $500 for parts and labor.

9. Can a bad NOx sensor cause other issues besides triggering OBDII code P11D2 GMC?

- Yes, a malfunctioning NOx sensor can lead to increased emissions, reduced engine performance, and potential damage to the catalytic converter over time.

10. How often should the NOx sensors be inspected or replaced to prevent OBDII code P11D2 GMC?

- It is recommended to have the NOx sensors inspected during regular maintenance intervals and replaced as needed based on manufacturer recommendations or if any issues arise.