AutoCodes – GMC – P11FE GMC

P11FE GMC Code - O2 Low Reference Circuit High 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: P11FE GMC indicates O2 Low Reference Circuit High 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 397

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
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Code P11FE 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 P11FE GMC - O2 Low Reference Circuit High Voltage (NOx Sensor 2) - AutoCodes.com — P11FE GMC Code - O2 Low Reference Circuit High Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11FE 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 P11FE 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 P11FE 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 P11FE GMC code?

Need more information on how to fix the P11FE GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific GMC Models

P11FE 2014 GMC Sierra — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE 2015 GMC Sierra — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE 2016 GMC Sierra — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE 2017 GMC Sierra — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE 2018 GMC Sierra — O2 Low Reference Circuit High 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 P11FE GMC Code

1. What are the common symptoms of OBDII code P11FE GMC related to the O2 Low Reference Circuit High Voltage (NOx Sensor 2)?

- Common symptoms may include poor engine performance, decreased fuel efficiency, rough idling, and an illuminated check engine light.

2. What are the possible causes of OBDII code P11FE GMC indicating an issue with the NOx Sensor 2?

- Possible causes may include a faulty NOx sensor, damaged wiring or connectors in the O2 sensor circuit, or issues with the engine control module.

3. How can I diagnose the O2 Low Reference Circuit High Voltage issue in NOx Sensor 2 triggering code P11FE GMC?

- Diagnosing this issue typically involves inspecting the NOx sensor 2, checking the wiring and connectors for damage, and using a scan tool to monitor sensor data.

4. Can a dirty or contaminated NOx sensor cause the OBDII code P11FE GMC to appear?

- Yes, a dirty or contaminated NOx sensor can lead to incorrect readings and trigger the O2 Low Reference Circuit High Voltage code (P11FE) for NOx Sensor 2.

5. What repair tips can help resolve OBDII code P11FE GMC associated with NOx Sensor 2 issues?

- Repair tips may include cleaning or replacing the NOx sensor, repairing damaged wiring, ensuring proper sensor connections, and resetting the fault code.

6. Is it safe to continue driving with OBDII code P11FE GMC related to NOx Sensor 2 problems?

- It is generally not recommended to drive for an extended period with this code unresolved, as it can lead to further engine damage and decreased fuel efficiency.

7. How critical is it to address the O2 Low Reference Circuit High Voltage issue in NOx Sensor 2 triggering code P11FE GMC?

- Addressing this issue promptly is important to ensure proper engine performance, emissions compliance, and avoid potential damage to other components.

8. Can a DIY enthusiast perform repairs for OBDII code P11FE GMC related to NOx Sensor 2, or is professional assistance necessary?

- Depending on the individual's skill level and access to tools, some repairs for this code may be DIY-friendly, but professional assistance is recommended for complex diagnostics and repairs.

9. Are there any recalls or technical service bulletins related to OBDII code P11FE GMC and NOx Sensor 2 issues?

- It is advisable to check with the manufacturer, dealership, or online databases for any relevant recalls or technical service bulletins regarding this specific OBDII code and sensor problem.

10. How can regular maintenance and inspections help prevent O2 Low Reference Circuit High Voltage issues with NOx Sensor 2 and OBDII code P11FE GMC?

- Regular maintenance, such as keeping the engine properly tuned, inspecting sensor wiring for damage, and using quality fuel, can help prevent issues leading to this specific OBDII code.