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P11D9 2016 GMC Sierra 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 2016 GMC Sierra 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 155

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
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Code P11D9 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 P11D9 2016 GMC Sierra - O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11D9 2016 GMC Sierra Code - O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D9 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 P11D9 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 P11D9 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 P11D9 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 P11D9 2016 GMC Sierra Code

1. What does OBDII code P11D9 mean on a 2016 GMC Sierra?

P11D9 indicates a problem with the O2 pump current control circuit for NOx Sensor 2, which monitors the nitrogen oxide levels in the exhaust system. Specifically, it points to a low voltage issue.

2. What are the symptoms of code P11D9 on a 2016 GMC Sierra?

Common symptoms include the check engine light turning on, reduced fuel efficiency, poor engine performance, and possible issues with emissions system operation.

3. What causes the P11D9 code on a GMC Sierra?

Possible causes include a faulty NOx sensor 2, wiring issues like damaged or corroded connectors, a malfunctioning O2 pump control circuit, or an issue with the engine control module (ECM).

4. How do you diagnose a P11D9 code?

Diagnosis involves scanning the vehicle for codes, inspecting wiring and connectors for damage, testing the NOx sensor 2 for proper operation, and checking the O2 pump control circuit for voltage and continuity.

5. Can I drive my 2016 GMC Sierra with a P11D9 code?

While the truck may still be drivable, itâ€™s not recommended as it can lead to reduced performance, increased emissions, and potential damage to other components in the emissions system.

6. How do you fix the P11D9 code on a GMC Sierra?

Repairs may include replacing the NOx sensor 2, repairing or replacing damaged wiring, cleaning or replacing corroded connectors, or reprogramming/updating the ECM if necessary.

7. How much does it cost to repair a P11D9 code?

The cost varies depending on the issue. Replacing a NOx sensor can cost $300â€“$600, while wiring repairs or ECM updates may vary based on labor rates and parts availability.

8. Does a faulty NOx sensor always cause the P11D9 code?

No, while a bad NOx sensor is a common cause, the issue could also stem from wiring problems, connector corrosion, or faults in the O2 pump control circuit.

9. Can a P11D9 code cause my GMC Sierra to fail an emissions test?

Yes, a P11D9 code indicates a problem with the emissions system, which can result in higher emissions and likely cause your vehicle to fail an emissions test.

10. How can I prevent the P11D9 code from recurring?

Regular maintenance, including inspecting and cleaning wiring and connectors, ensuring proper operation of the emissions system, and addressing issues promptly, can help prevent this code from returning.