AutoCodes – Generic – P11FE

P11FE 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 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 760

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

What does this mean?

What are the Possible Causes of the DTC P11FE?

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?

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 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 code?

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

Need Help with the Code?

Get the P11FE code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P11FE Buick — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE Cadillac — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE Chevrolet — O2 Low Reference Circuit High Voltage (NOx Sensor 2)
P11FE GMC — 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 Code

1. What are the common symptoms of OBDII code P11FE?

- Common symptoms include poor engine performance, increased fuel consumption, rough idling, and the illumination of the check engine light.

2. What causes the O2 Low Reference Circuit High Voltage (NOx Sensor 2) code P11FE?

- The P11FE code is typically triggered by issues such as a faulty NOx sensor, damaged wiring or connectors, or a malfunctioning engine control module (ECM).

3. How serious is the OBDII code P11FE?

- While the P11FE code may not cause immediate harm to the vehicle, it can lead to decreased fuel efficiency and increased emissions. It is recommended to address this issue promptly.

4. Can I continue driving with the P11FE code present?

- It is not advisable to continue driving with the P11FE code active, as it can affect the overall performance of the vehicle and may lead to further damage if left unresolved.

5. How do I diagnose the O2 Low Reference Circuit High Voltage (NOx Sensor 2) code P11FE?

- Diagnosis typically involves using an OBDII scanner to read the code, followed by inspecting the NOx sensor, wiring, and connectors for any visible damage or issues.

6. How can I repair the P11FE code?

- Repair options may include replacing the NOx sensor, repairing or replacing damaged wiring or connectors, or reprogramming the ECM to address any software-related issues.

7. Can I reset the P11FE code on my own?

- While you can clear the code with an OBDII scanner, it is important to address the underlying issue causing the code to prevent it from reoccurring.

8. Are there any DIY tips for fixing the P11FE code?

- DIY tips may include checking for loose connections, inspecting the sensor for physical damage, and ensuring the sensor is receiving the correct voltage.

9. Is the O2 Low Reference Circuit High Voltage (NOx Sensor 2) code P11FE a common issue in certain vehicle makes and models?

- The P11FE code may be more common in vehicles equipped with NOx sensors, particularly in newer models that have advanced emissions control systems.

10. How much does it typically cost to repair the P11FE code?

- The cost of repairing the P11FE code can vary depending on the underlying issue, but it may range from $200 to $500 for parts and labor.

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