AutoCodes – GMC – P11D8 GMC

P11D8 GMC Code - O2 Pump Current Control Circuit (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: P11D8 GMC indicates O2 Pump Current Control Circuit (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 834

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 P11D8 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 P11D8 GMC - O2 Pump Current Control Circuit (NOx Sensor 2) - AutoCodes.com — P11D8 GMC Code - O2 Pump Current Control Circuit (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D8 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 P11D8 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 P11D8 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 P11D8 GMC code?

Need more information on how to fix the P11D8 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11D8 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P11D8 2014 GMC Sierra — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 2015 GMC Sierra — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 2016 GMC Sierra — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 2017 GMC Sierra — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 2018 GMC Sierra — O2 Pump Current Control Circuit (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 P11D8 GMC Code

1. What are the common symptoms of OBDII code P11D8 GMC?

- Common symptoms include poor engine performance, increased fuel consumption, rough idling, and illuminated Check Engine Light.

2. What does the OBDII code P11D8 GMC indicate?

- The code indicates a malfunction in the O2 Pump Current Control Circuit related to NOx Sensor 2.

3. What are the possible causes of OBDII code P11D8 GMC?

- Possible causes include a faulty NOx sensor, damaged wiring or connectors, a defective O2 pump, or issues with the engine control module (ECM).

4. How can I diagnose OBDII code P11D8 GMC?

- Diagnosis involves using an OBDII scanner to retrieve the code, inspecting the NOx sensor and related components, and testing the circuit for continuity and voltage.

5. Can I continue driving with OBDII code P11D8 GMC?

- It is not recommended to continue driving with this code as it can lead to further damage to the vehicle and potentially affect emissions levels.

6. How can I repair OBDII code P11D8 GMC?

- Repair options include replacing the NOx sensor, repairing or replacing damaged wiring or connectors, replacing the O2 pump, or reprogramming the ECM if necessary.

7. Is it possible to reset OBDII code P11D8 GMC without fixing the issue?

- While you can clear the code temporarily, it is important to address the underlying issue to prevent further problems with your vehicle.

8. How much does it cost to fix OBDII code P11D8 GMC?

- The cost of repairs can vary depending on the specific issue causing the code, but it is recommended to consult a professional mechanic for an accurate diagnosis and cost estimate.

9. Can a DIY enthusiast fix OBDII code P11D8 GMC?

- Depending on your experience and tools, you may be able to address simpler causes like damaged wiring or connectors. However, complex issues may require professional assistance.

10. How often does OBDII code P11D8 GMC occur in GMC vehicles?

- The occurrence of this specific code can vary, but it is not uncommon in GMC vehicles equipped with NOx sensors and O2 pumps.