AutoCodes – GMC – P11C8 GMC

P11C8 GMC Code - NOx Sensor 2 Heater Ground Circuit High

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: P11C8 GMC indicates NOx Sensor 2 Heater Ground Circuit High.
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 380

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 P11C8 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 P11C8 GMC - NOx Sensor 2 Heater Ground Circuit High - AutoCodes.com — P11C8 GMC Code - NOx Sensor 2 Heater Ground Circuit High

What does this mean?

What are the Possible Causes of the DTC P11C8 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 P11C8 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 P11C8 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 P11C8 GMC code?

Need more information on how to fix the P11C8 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11C8 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P11C8 2014 GMC Sierra — NOx Sensor 2 Heater Ground Circuit High
P11C8 2015 GMC Sierra — NOx Sensor 2 Heater Ground Circuit High
P11C8 2016 GMC Sierra — NOx Sensor 2 Heater Ground Circuit High
P11C8 2017 GMC Sierra — NOx Sensor 2 Heater Ground Circuit High
P11C8 2018 GMC Sierra — NOx Sensor 2 Heater Ground Circuit High

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 P11C8 GMC Code

1. What are the common symptoms of OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

The common symptoms include the Check Engine light illuminating on the dashboard, reduced engine performance, and potential failures to pass emissions testing.

2. What can cause the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

This code is typically triggered by a malfunction in the NOx sensor 2 heater ground circuit, which may be caused by wiring issues, a faulty sensor, or corrosion in the electrical connections.

3. How serious is the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

While the vehicle may still be operable with this code present, ignoring it can lead to decreased fuel efficiency, increased emissions, and potential damage to the catalytic converter over time.

4. Can I continue driving my vehicle with the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

It is generally not recommended to continue driving the vehicle with this code present, as it can lead to further damage and potentially cause the vehicle to fail emissions testing.

5. How can I diagnose the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

Diagnosis typically involves using a scan tool to retrieve the code, inspecting the NOx sensor 2 heater circuit for faults, checking the wiring and connectors for damage, and testing the sensor itself.

6. Can I repair the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High myself?

While some DIY enthusiasts may be able to address this issue by checking and repairing the wiring or connectors, it is recommended to consult a professional mechanic for a proper diagnosis and repair.

7. What are the repair options for the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

Repair options may include repairing or replacing damaged wiring, cleaning corroded connectors, replacing the NOx sensor 2 if faulty, or resetting the fault code after addressing the underlying issue.

8. How much does it cost to fix the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High?

The cost of fixing this issue can vary depending on the root cause of the problem, the extent of the repairs needed, and whether you choose to DIY or seek professional help. Costs may range from a few hundred to over a thousand dollars.

9. Can a faulty NOx sensor 2 cause other problems in the vehicle?

Yes, a faulty NOx sensor 2 can lead to poor engine performance, increased emissions, and potential damage to the catalytic converter if left unresolved, impacting the overall drivability and efficiency of the vehicle.

10. How can I prevent the OBDII code P11C8 GMC NOx Sensor 2 Heater Ground Circuit High from recurring?

Regular maintenance, such as checking and cleaning electrical connections, inspecting the sensor for signs of wear, and addressing any wiring issues promptly, can help prevent the recurrence of this code.