AutoCodes – Generic – P11D2

P11D2 Code - O2 Signal 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: P11D2 indicates O2 Signal 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 716

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 P11D2 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 P11D2 - O2 Signal Circuit High Voltage (NOx Sensor 2) - AutoCodes.com — P11D2 Code - O2 Signal Circuit High Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D2?

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 P11D2?

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 P11D2 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 P11D2 code?

Need more information on how to fix the P11D2 code? Get Access to Factory Service Manuals

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Information for Specific Makes

P11D2 Buick — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 Cadillac — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 Chevrolet — O2 Signal Circuit High Voltage (NOx Sensor 2)
P11D2 GMC — O2 Signal 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 P11D2 Code

1. What are the common symptoms of OBDII code P11D2 (O2 Signal Circuit High Voltage - NOx Sensor 2)?

- Common symptoms include poor engine performance, decreased fuel efficiency, rough idling, and the illumination of the Check Engine light.

2. What are the possible causes of OBDII code P11D2?

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

3. How can I diagnose OBDII code P11D2?

- Diagnose the code by using an OBDII scanner to read the fault codes, inspecting the NOx sensor and its wiring for damage, and checking the connector for corrosion or loose connections.

4. Can driving with OBDII code P11D2 cause further damage to the vehicle?

- Continuing to drive with this code can potentially lead to increased emissions, reduced fuel efficiency, and damage to the catalytic converter or other engine components over time.

5. How can I repair OBDII code P11D2?

- Repair options include replacing the NOx sensor, repairing any damaged wiring or connectors, clearing the fault codes, and performing a test drive to ensure the issue has been resolved.

6. Is it safe to drive my vehicle with OBDII code P11D2?

- It is generally not recommended to drive the vehicle with this code active, as it can affect engine performance and emissions. It is best to address the issue promptly.

7. How much does it typically cost to fix OBDII code P11D2?

- The cost of repairing this code can vary depending on the exact cause of the issue, but it may range from $200 to $500 including parts and labor.

8. Can a DIY enthusiast with basic automotive knowledge fix OBDII code P11D2?

- While some DIY enthusiasts may be able to address this code themselves by replacing the NOx sensor or checking the wiring, it is recommended to consult a professional mechanic for accurate diagnosis and repair.

9. How long does it take to repair OBDII code P11D2?

- The repair time for this code can vary depending on the extent of the issue and the availability of parts, but it typically takes a few hours to half a day to complete the repair.

10. Will resetting the Check Engine light resolve OBDII code P11D2?

- Resetting the Check Engine light may temporarily turn off the light, but it will not fix the underlying issue causing OBDII code P11D2. It is important to diagnose and repair the problem to prevent further issues.