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P11D9 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado 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 302

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 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado - O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11D9 2018 Chevrolet Silverado Code - O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D9 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado code?

Need more information on how to fix the P11D9 2018 Chevrolet Silverado code? Get Access to Factory Service Manuals

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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 2018 Chevrolet Silverado Code

What does the OBDII code P11D9 mean on a 2018 Chevrolet Silverado?

Code P11D9 indicates "O2 Pump Current Control Circuit Low Voltage (NOx Sensor 2)" and refers to an issue with the second NOx sensor, specifically low voltage in the oxygen pump circuit.

What are the symptoms of code P11D9 on a 2018 Chevrolet Silverado?

Symptoms may include the check engine light turning on, reduced fuel efficiency, decreased engine performance, and possible emissions test failure.

What causes the P11D9 code to appear on a 2018 Chevrolet Silverado?

Common causes include a faulty NOx sensor 2, wiring or connector issues in the sensor circuit, or a malfunction in the engine control module (ECM).

Can I drive my 2018 Chevrolet Silverado with code P11D9?

While the vehicle may still be drivable, it is not recommended because the issue could lead to increased emissions and potential damage to other components.

How is the P11D9 code diagnosed on a 2018 Chevrolet Silverado?

A technician will use a scan tool to confirm the code, inspect the wiring and connectors for damage, test the NOx sensorâ€™s resistance, and check the ECM for proper operation.

How do you fix code P11D9 on a 2018 Chevrolet Silverado?

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

How much does it cost to fix the P11D9 code on a 2018 Chevrolet Silverado?

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

Can a failing NOx sensor cause additional problems in my Silverado?

Yes, a failing NOx sensor can lead to poor engine performance, reduced fuel efficiency, and potential damage to the catalytic converter over time.

Is the P11D9 code covered under warranty for a 2018 Chevrolet Silverado?

It depends on your warranty coverage. Emission components like NOx sensors may be covered under the federal emissions warranty or an extended warranty.

What tools are needed to repair code P11D9 on a 2018 Chevrolet Silverado?

Common tools include an OBDII scan tool, a multimeter for testing circuits, and basic hand tools to remove and replace the NOx sensor or wiring.