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P11D1 Chevrolet Code - O2 Signal 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: P11D1 Chevrolet indicates O2 Signal 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 670

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 P11D1 Chevrolet 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 P11D1 Chevrolet - O2 Signal Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11D1 Chevrolet Code - O2 Signal Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D1 Chevrolet?

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 P11D1 Chevrolet?

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 P11D1 Chevrolet 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 P11D1 Chevrolet code?

Need more information on how to fix the P11D1 Chevrolet code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Chevrolet Models

P11D1 2014 Chevrolet Silverado — O2 Signal Circuit Low Voltage (NOx Sensor 2)
P11D1 2015 Chevrolet Silverado — O2 Signal Circuit Low Voltage (NOx Sensor 2)
P11D1 2016 Chevrolet Silverado — O2 Signal Circuit Low Voltage (NOx Sensor 2)
P11D1 2017 Chevrolet Silverado — O2 Signal Circuit Low Voltage (NOx Sensor 2)
P11D1 2018 Chevrolet Silverado — O2 Signal 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 P11D1 Chevrolet Code

What does the OBDII code P11D1 mean for a Chevrolet vehicle?

The OBDII code P11D1 indicates that there is a low voltage signal from the NOx sensor 2, which is responsible for monitoring nitrogen oxide levels in the exhaust.

What are the common symptoms of a P11D1 code?

Common symptoms include illuminated check engine light, reduced engine performance, increased emissions, and possible failed emissions test.

What could cause the P11D1 code to trigger?

Causes may include a faulty NOx sensor 2, issues with the wiring or connectors related to the sensor, exhaust system leaks, or a malfunctioning engine control module (ECM).

How can I diagnose the P11D1 code?

To diagnose the P11D1 code, start by using an OBDII scanner to confirm the code. Then, inspect the NOx sensor's wiring and connectors for damage, check for exhaust leaks, and test the sensor's voltage output.

What repairs are needed to fix a P11D1 code?

Repairs may involve replacing the NOx sensor 2, repairing damaged wiring or connectors, fixing exhaust leaks, or, in some cases, reprogramming or replacing the ECM.

Can I drive my Chevrolet with a P11D1 code?

While you can technically drive with a P11D1 code, it is not recommended as it may lead to decreased engine performance and increased emissions.

How can I clear the P11D1 code after repairs?

After completing the necessary repairs, you can clear the P11D1 code using an OBDII scanner by selecting the option to clear or erase codes.

Is it safe to ignore the P11D1 code?

Ignoring the P11D1 code is not safe as it can lead to further engine issues, reduced fuel efficiency, and potential damage to emissions components.

Will a P11D1 code affect my vehicle's fuel economy?

Yes, a P11D1 code can negatively affect fuel economy due to improper fuel-air mixture adjustments made by the engine control module in response to the faulty NOx sensor.