AutoCodes – GMC – P11D1 2018 GMC Sierra

P11D1 2018 GMC Sierra 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 2018 GMC Sierra 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 151

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P11D1 2018 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 P11D1 2018 GMC Sierra - O2 Signal Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11D1 2018 GMC Sierra Code - O2 Signal Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D1 2018 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 P11D1 2018 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 P11D1 2018 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 P11D1 2018 GMC Sierra code?

Need more information on how to fix the P11D1 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11D1 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 2018 GMC Sierra Code

1. What are common symptoms of OBDII code P11D1 in a 2018 GMC Sierra?

Common symptoms include poor fuel economy, rough idling, decreased engine performance, and the illumination of the check engine light.

2. What causes the OBDII code P11D1 in a 2018 GMC Sierra related to the O2 signal circuit low voltage (NOx Sensor 2)?

The code P11D1 is typically triggered by issues such as a faulty NOx sensor, damaged wiring in the O2 sensor circuit, or a problem with the vehicle's engine control module (ECM).

3. How can I diagnose the O2 signal circuit low voltage issue in a 2018 GMC Sierra triggering code P11D1?

Diagnosing this problem involves inspecting the NOx sensor and its wiring for damage, checking the ECM for any faults, and using a diagnostic scanner to monitor the sensor's voltage output.

4. Can a DIY enthusiast repair the O2 signal circuit low voltage problem associated with code P11D1 in a 2018 GMC Sierra?

While some basic troubleshooting like checking for loose connections or damaged wiring can be done by a DIY enthusiast, advanced repairs involving sensor replacement or ECM reprogramming may require professional expertise.

5. What are the potential consequences of ignoring OBDII code P11D1 in a 2018 GMC Sierra?

Ignoring code P11D1 can lead to poor engine performance, reduced fuel efficiency, and potential damage to other engine components over time, ultimately resulting in costly repairs.

6. Is it safe to continue driving a 2018 GMC Sierra with the O2 signal circuit low voltage issue causing code P11D1?

It is not recommended to drive the vehicle for an extended period with this issue unresolved, as it can affect the overall performance and efficiency of the engine, potentially leading to more severe problems.

7. How much does it typically cost to repair the O2 signal circuit low voltage problem triggering code P11D1 in a 2018 GMC Sierra?

The cost of repairs can vary depending on the exact cause of the issue, but it may range from a few hundred to a few thousand dollars, including parts and labor.

8. Can a software update fix the O2 signal circuit low voltage issue linked to code P11D1 in a 2018 GMC Sierra?

In some cases, a software update to the ECM can resolve the problem if it was caused by a software glitch. It is advisable to consult with a qualified mechanic or dealership for guidance on this matter.

9. Are there any preventive measures to avoid encountering OBDII code P11D1 in a 2018 GMC Sierra?

Regular maintenance, such as checking and replacing sensors according to the manufacturer's recommendations, inspecting wiring for damage, and addressing any engine performance issues promptly, can help prevent the occurrence of code P11D1.

10. What is the typical lifespan of the NOx sensor in a 2018 GMC Sierra before it may trigger code P11D1?

The lifespan of the NOx sensor can vary, but it is generally recommended to replace it every 100,000 miles or as indicated by the manufacturer to prevent issues like code P11D1 from occurring.