Engine-CodesGMC – P11FC 2017 GMC Sierra

P11FC 2017 GMC Sierra Code - O2 Low Reference Circuit (NOx Sensor 2)

Quick Answer

The P11FC diagnostic trouble code for a 2017 GMC Sierra relates to the O2 low reference circuit, specifically for NOx Sensor 2. Common causes include Faulty NOx sensor, Wiring or connector issues in the O2 sensor circuit, Exhaust leaks near the sensor. 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
P11FC 2017 GMC Sierra indicates O2 Low Reference Circuit (NOx Sensor 2).
Common causes
Common causes include Faulty NOx sensor, Wiring or connector issues in the O2 sensor circuit, Exhaust leaks near the sensor.
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.
Table of contents Created and updated by William Orellana on Aug 19, 2024
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Code P11FC 2017 GMC Sierra Description

The P11FC diagnostic trouble code for a 2017 GMC Sierra relates to the O2 low reference circuit, specifically for NOx Sensor 2. This code indicates a problem with the oxygen sensor's low reference circuit, which measures the oxygen levels in the exhaust gases to help regulate the air-fuel mixture. In this case, the issue is specific to the second NOx sensor, which is responsible for monitoring nitrogen oxide levels in the exhaust system.

OBDII Code P11FC 2017 GMC Sierra - O2 Low Reference Circuit (NOx Sensor 2)
P11FC 2017 GMC Sierra Code - O2 Low Reference Circuit (NOx Sensor 2)

Common Causes of P11FC 2017 GMC Sierra

  1. Faulty NOx sensor
  2. Wiring or connector issues in the O2 sensor circuit
  3. Exhaust leaks near the sensor
  4. Engine running rich or lean
  5. ECM (Engine Control Module) failure

Symptoms of P11FC 2017 GMC Sierra

  1. Rough idling or hesitation during acceleration
  2. Decreased fuel efficiency
  3. Illumination of the check engine light
  4. Failed emissions test
  5. Reduced engine power

How to Fix P11FC 2017 GMC Sierra

  1. Diagnose the specific cause of the issue using a scan tool and multimeter to test the sensor, wiring, and connectors.
  2. Replace the faulty NOx sensor if it is determined to be the cause of the problem.
  3. Repair any damaged wiring or connectors in the O2 sensor circuit.
  4. Check for and repair any exhaust leaks near the sensor.
  5. Reset the vehicle's ECM to clear the trouble code and monitor the vehicle to ensure the issue has been resolved.

Cost to Fix P11FC 2017 GMC Sierra

The cost to repair a P11FC code on a 2017 GMC Sierra can vary depending on the specific cause of the issue. On average, the cost of replacing a NOx sensor can range from $200 to $500, including parts and labor. Additional costs may apply if there are wiring or connector issues that need to be repaired. It's important to consider the labor rates at your local auto repair shop, as well as any diagnostic time required to pinpoint the exact cause of the problem.

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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 P11FC 2017 GMC Sierra Code

1. What does OBDII code P11FC mean on a 2017 GMC Sierra?

P11FC indicates an issue with the O2 low reference circuit for NOx Sensor 2, which monitors nitrogen oxide levels in the exhaust.

2. What are the symptoms of code P11FC in a 2017 GMC Sierra?

Symptoms may include the check engine light turning on, reduced fuel efficiency, increased emissions, and potential performance issues.

3. What causes code P11FC to appear?

Common causes include a faulty NOx Sensor 2, damaged wiring or connectors in the O2 low reference circuit, or issues with the ECM (engine control module).

4. Can I drive my 2017 GMC Sierra with code P11FC?

Driving with this code is possible but not recommended, as it could lead to increased emissions, reduced performance, and potential damage to other components.

5. How do I diagnose code P11FC in a 2017 GMC Sierra?

Diagnosis involves scanning the vehicle with an OBDII tool, inspecting the wiring and connectors for damage, and testing the NOx Sensor 2 and its circuits.

6. How do I fix code P11FC on a 2017 GMC Sierra?

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

7. How much does it cost to fix code P11FC on a 2017 GMC Sierra?

Repair costs vary but typically range from $300 to $800, depending on whether the NOx sensor or wiring needs replacement.

8. Is code P11FC covered under warranty for a 2017 GMC Sierra?

If your vehicle is still under the emissions warranty, the repair might be covered. Check with your dealership for confirmation.

9. What tools are needed to troubleshoot code P11FC?

Tools include an OBDII scanner, multimeter for testing wiring, and potentially a NOx sensor-specific diagnostic tool.

10. Can a dirty exhaust system cause code P11FC?

While unlikely, an excessively dirty or clogged exhaust system could contribute to sensor issues, so it’s worth inspecting the exhaust if this code appears.

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