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P11FE Buick 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 Buick 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 343

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

What does this mean?

What are the Possible Causes of the DTC P11FE Buick?

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 Buick?

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 Buick 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.

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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 P11FE Buick Code

1. What does the OBDII code P11FE mean for a Buick?

P11FE indicates that the O2 low reference circuit for NOx Sensor 2 is experiencing high voltage, which can affect emissions performance.

2. What are the common symptoms of the P11FE code?

Symptoms may include an illuminated check engine light, reduced fuel efficiency, poor engine performance, and failed emissions tests.

3. What causes the P11FE code to trigger?

Common causes include a faulty NOx Sensor 2, wiring issues such as damaged or corroded connectors, or a malfunctioning engine control module (ECM).

4. Can I drive my Buick with the P11FE code?

While the car may still be drivable, ignoring the issue can lead to increased emissions, reduced performance, and potential long-term engine or catalytic converter damage.

5. How is the P11FE code diagnosed?

A mechanic will use a scan tool to verify the code, inspect the wiring and connectors for damage, and test the NOx Sensor 2 for proper operation.

6. How do I fix the P11FE code?

Repairs may involve replacing the NOx Sensor 2, repairing or replacing damaged wiring or connectors, or reprogramming/updating the ECM if needed.

7. What tools are needed to repair the P11FE code?

Common tools include an OBDII scanner, multimeter for testing voltage, and basic hand tools for sensor or wiring replacement.

8. How much does it cost to fix the P11FE code on a Buick?

Repair costs can range from $200 to $600 or more, depending on whether the NOx sensor, wiring, or ECM needs repair or replacement.

9. Can a dirty NOx sensor cause the P11FE code?

Yes, a contaminated or dirty NOx sensor can cause incorrect readings, leading to the P11FE code.

10. Is the P11FE code covered under warranty?

It depends on your vehicleâ€™s warranty. Emission-related components like NOx sensors may be covered under the emissions warranty. Check with your dealership for details.