AutoCodes – Generic – P11D0

P11D0 Code - O2 Signal Circuit (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: P11D0 indicates O2 Signal Circuit (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 1,784

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 P11D0 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 P11D0 - O2 Signal Circuit (NOx Sensor 2) - AutoCodes.com — P11D0 Code - O2 Signal Circuit (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D0?

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 P11D0?

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 P11D0 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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Information for Specific Makes

P11D0 Buick — O2 Signal Circuit (NOx Sensor 2)
P11D0 Cadillac — O2 Signal Circuit (NOx Sensor 2)
P11D0 Chevrolet — O2 Signal Circuit (NOx Sensor 2)
P11D0 GMC — O2 Signal Circuit (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 P11D0 Code

1. What are the common symptoms of OBDII code P11D0 (O2 Signal Circuit - NOx Sensor 2)?

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

2. What can cause OBDII code P11D0 to trigger?

Possible causes of P11D0 include a faulty NOx sensor 2, damaged wiring or connectors in the O2 signal circuit, or a malfunctioning engine control module (ECM).

3. How can I diagnose the O2 Signal Circuit issue related to code P11D0?

Diagnosing P11D0 involves using a scan tool to retrieve the code, conducting a visual inspection of the sensor and wiring, and performing electrical tests to check for continuity and voltage.

4. Is it safe to continue driving with OBDII code P11D0 active?

It is not recommended to drive with P11D0 present, as it can lead to further damage to the vehicle and compromise emissions control.

5. Can I repair OBDII code P11D0 (O2 Signal Circuit - NOx Sensor 2) myself?

Depending on your skill level, you may be able to repair P11D0 yourself by replacing the NOx sensor 2, repairing damaged wiring, or resetting the ECM after fixing the issue.

6. Will resetting the check engine light resolve OBDII code P11D0 permanently?

Resetting the check engine light may temporarily clear the code, but if the underlying issue causing P11D0 is not addressed, the code is likely to reappear.

7. How much does it typically cost to fix OBDII code P11D0?

The cost of fixing P11D0 can vary depending on the specific cause of the issue, but it may range from $200 to $500 at a repair shop, including parts and labor.

8. Can a bad NOx sensor 2 cause other problems in the vehicle?

A faulty NOx sensor 2 can affect the vehicle's emissions control system, engine performance, and fuel efficiency, leading to potential issues with passing emissions tests and overall drivability.

9. How long does it take to repair OBDII code P11D0 (O2 Signal Circuit - NOx Sensor 2)?

The repair time for P11D0 can vary based on the complexity of the issue and the availability of parts, but it typically takes a few hours to a day to complete the repair.

10. Are there any preventive measures to avoid OBDII code P11D0 in the future?

Regularly maintaining your vehicle, checking for wiring damage, and ensuring timely sensor replacements can help prevent issues like P11D0 from occurring in the future.