AutoCodes – GMC – P11D9 GMC

P11D9 GMC Code - O2 Pump Current Control 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: P11D9 GMC indicates O2 Pump Current Control 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 427

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 P11D9 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 P11D9 GMC - O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11D9 GMC Code - O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D9 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 P11D9 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 P11D9 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 P11D9 GMC code?

Need more information on how to fix the P11D9 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific GMC Models

P11D9 2014 GMC Sierra — O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)
P11D9 2015 GMC Sierra — O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)
P11D9 2016 GMC Sierra — O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)
P11D9 2017 GMC Sierra — O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)
P11D9 2018 GMC Sierra — O2 Pump Current Control Circuit Low 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 P11D9 GMC Code

1. What are the common symptoms of OBDII code P11D9 GMC?

The common symptoms of code P11D9 GMC include poor engine performance, decreased fuel efficiency, and potential illumination of the Check Engine Light.

2. What can cause the O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2) error code?

Potential causes of the P11D9 code include a faulty NOx sensor, damaged wiring or connectors in the O2 pump circuit, or issues with the powertrain control module.

3. How serious is the OBDII code P11D9 GMC?

While the P11D9 code may not cause immediate harm to the vehicle, it can lead to increased emissions and potential compliance issues during emissions testing. It is recommended to address this code promptly.

4. Can I continue driving my vehicle with the P11D9 error code?

It is generally safe to drive the vehicle with the P11D9 code, but it is advisable to address the underlying issue as soon as possible to prevent potential damage to the emissions control system.

5. How can I diagnose and repair the O2 Pump Current Control Circuit Low Voltage error code?

Diagnosis typically involves inspecting the NOx sensor, checking the O2 pump circuit for damage, and scanning the powertrain control module for related error codes. Repair may involve replacing the faulty sensor or repairing wiring issues.

6. Can I reset the P11D9 code with an OBDII scanner?

Yes, you can reset the P11D9 code using an OBDII scanner. However, it is important to address the root cause of the code to prevent it from reoccurring.

7. Are there any DIY tips for fixing the P11D9 GMC code?

DIY tips for addressing the P11D9 code include checking and cleaning the sensor connections, inspecting the wiring for damage, and ensuring proper grounding of the O2 pump circuit.

8. How much does it cost to repair the O2 Pump Current Control Circuit Low Voltage error code?

The cost of repairing the P11D9 code can vary depending on the root cause of the issue, the labor rates in your area, and whether you choose to address the problem yourself or seek professional help.

9. Will fixing the P11D9 code improve my vehicle's performance and fuel efficiency?

Addressing the P11D9 code can potentially improve your vehicle's performance and fuel efficiency by ensuring proper operation of the emissions control system. However, the impact may vary depending on the specific issue causing the code.