AutoCodes – Buick – P11FD Buick

P11FD Buick Code - O2 Low Reference Circuit Low 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: P11FD Buick indicates O2 Low Reference Circuit Low 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 312

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 P11FD 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 P11FD Buick - O2 Low Reference Circuit Low Voltage (NOx Sensor 2) - AutoCodes.com — P11FD Buick Code - O2 Low Reference Circuit Low Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11FD 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 P11FD 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 P11FD 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 P11FD Buick Code

1. What are the common symptoms of OBDII code P11FD in a Buick related to the O2 Low Reference Circuit Low Voltage (NOx Sensor 2)?

- Common symptoms include poor engine performance, reduced fuel efficiency, and the illumination of the check engine light.

2. What are the potential causes of OBDII code P11FD in a Buick indicating O2 Low Reference Circuit Low Voltage (NOx Sensor 2)?

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

3. How can I diagnose OBDII code P11FD in my Buick associated with the O2 Low Reference Circuit Low Voltage (NOx Sensor 2)?

- Diagnosis typically involves using an OBDII scanner to retrieve the specific fault code, inspecting the NOx sensor and related wiring for damage, and testing the sensor's voltage output.

4. What are some repair tips for fixing OBDII code P11FD in a Buick related to the O2 Low Reference Circuit Low Voltage (NOx Sensor 2)?

- Repair tips may include replacing the faulty NOx sensor, repairing any damaged wiring or connectors, and ensuring proper connections in the O2 sensor circuit.

5. Can driving with OBDII code P11FD in a Buick indicating O2 Low Reference Circuit Low Voltage (NOx Sensor 2) cause further damage to the vehicle?

- Continuing to drive with this fault code may lead to decreased engine efficiency, potential damage to the catalytic converter, and increased emissions.

6. How important is it to address OBDII code P11FD in a Buick related to the O2 Low Reference Circuit Low Voltage (NOx Sensor 2) promptly?

- It is crucial to address this code promptly to prevent further damage to the vehicle, ensure optimal engine performance, and maintain fuel efficiency.

7. Are there any common mistakes to avoid when dealing with OBDII code P11FD in a Buick associated with the O2 Low Reference Circuit Low Voltage (NOx Sensor 2)?

- Common mistakes to avoid include ignoring the check engine light, overlooking sensor wiring issues, and attempting to clear the fault code without addressing the underlying problem.

8. Can I reset OBDII code P11FD in my Buick indicating O2 Low Reference Circuit Low Voltage (NOx Sensor 2) without repairing the issue?

- While you can clear the fault code temporarily, it is essential to diagnose and repair the underlying problem to prevent the code from reoccurring.

9. How much does it typically cost to repair OBDII code P11FD in a Buick related to the O2 Low Reference Circuit Low Voltage (NOx Sensor 2)?

- The cost of repair can vary depending on the exact cause of the issue, but it may involve replacing the NOx sensor, repairing wiring, or addressing ECM issues.

10. Is it possible to prevent OBDII code P11FD in a Buick indicating O2 Low Reference Circuit Low Voltage (NOx Sensor 2) from occurring in the future?

- Regular vehicle maintenance, timely sensor inspections, and addressing any related warning signs promptly can help prevent the recurrence of this fault code.