AutoCodes – GMC – P11AF GMC

P11AF GMC Code - N02S 2 Performance Signal High During Moderate Load Sensor 2

Quick Answer

The reductant system uses two Nitrogen Oxide (NOx) sensors to monitor the amount of NOx in the engine's exhaust gas. Common causes include Faulty Nitrogen Oxide (NOx) Sensor, Nitrogen Oxide (NOx) Sensor harness is open or shorted, Nitrogen Oxide (NOx) Sensor 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: P11AF GMC indicates N02S 2 Performance Signal High During Moderate Load Sensor 2.
Common causes: Common causes include Faulty Nitrogen Oxide (NOx) Sensor, Nitrogen Oxide (NOx) Sensor harness is open or shorted, Nitrogen Oxide (NOx) Sensor 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 2,003

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 Aug 28, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P11AF GMC Description

The reductant system uses two Nitrogen Oxide (NOx) sensors to monitor the amount of NOx in the engine's exhaust gas. The first sensor is located at the outlet of the turbocharger and monitors the engine out NOx level. The second NOx sensor is located between the Selective Catalytic Reduction (SCR) and the Diesel Particulate Filter (DPF) and monitors NOx levels downstream of the SCR. The second NOx sensor also provides the Engine Control Module (ECM) with information on the exhaust oxygen level during DPF regeneration.
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 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 (DEF) or reductant added by varying the reductant injector duty cycle in response to changes in engine exhaust out 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.

OBDII Code P11AF GMC - N02S 2 Performance Signal High During Moderate Load Sensor 2 - AutoCodes.com — P11AF GMC Code - N02S 2 Performance Signal High During Moderate Load Sensor 2

What does this mean?

What are the Possible Causes of the DTC P11AF GMC?

Faulty Nitrogen Oxide (NOx) Sensor
Nitrogen Oxide (NOx) Sensor harness is open or shorted
Nitrogen Oxide (NOx) Sensor circuit poor electrical connection

How to Fix the DTC P11AF 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 P11AF 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 P11AF GMC 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 P11AF GMC Code

1. What are common symptoms of OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Common symptoms include poor engine performance, reduced fuel efficiency, and potential stalling or hesitation during acceleration.

2. What are the possible causes of OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Possible causes may include a faulty oxygen sensor, issues with the fuel system, vacuum leaks, or problems with the engine's air intake system.

3. How can I diagnose OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Diagnosis typically involves using a scan tool to read the code, checking for related codes, inspecting the oxygen sensor, and testing the fuel system components for proper operation.

4. Can a dirty air filter trigger OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Yes, a dirty air filter can restrict airflow to the engine, affecting the air-fuel mixture and potentially leading to the triggering of this code.

5. What are some repair tips for addressing OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Repair tips may include replacing the oxygen sensor, cleaning or replacing the air filter, checking for vacuum leaks, inspecting the fuel injectors, and ensuring proper fuel pressure.

6. Can driving with OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2 cause further damage to the vehicle?

- Continuing to drive with this code can potentially lead to decreased engine performance, reduced fuel efficiency, and further damage to engine components over time.

7. How much does it typically cost to repair OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

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

8. Is it safe to ignore OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Ignoring this code can lead to poor engine performance and reduced fuel efficiency, so it is recommended to address the underlying issue promptly to prevent further damage.

9. Can a DIY enthusiast address OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- Depending on the skill level and tools available, some DIY enthusiasts may be able to address this code by following repair guides and using diagnostic equipment.

10. How long does it typically take to repair OBDII code P11AF GMC N02S 2 Performance Signal High During Moderate Load Sensor 2?

- The repair time can vary based on the specific issue causing the code, but it may take a few hours to a full day to diagnose and repair the underlying problem.