AutoCodes – Generic – P11C0

P11C0 Code - O2 Reference Voltage 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: P11C0 indicates O2 Reference Voltage 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 2,373

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 P11C0 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 P11C0 - O2 Reference Voltage Circuit High Voltage (NOx Sensor 2) - AutoCodes.com — P11C0 Code - O2 Reference Voltage Circuit High Voltage (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11C0?

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 P11C0?

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 P11C0 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 P11C0 code?

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Information for Specific Makes

P11C0 Buick — O2 Reference Voltage Circuit High Voltage (NOx Sensor 2)
P11C0 Cadillac — O2 Reference Voltage Circuit High Voltage (NOx Sensor 2)
P11C0 Chevrolet — O2 Reference Voltage Circuit High Voltage (NOx Sensor 2)
P11C0 GMC — O2 Reference Voltage 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 P11C0 Code

1. What are common symptoms of OBDII code P11C0?

Symptoms may include decreased fuel efficiency, rough idling, engine misfires, and illuminated check engine light.

2. What can cause the O2 Reference Voltage Circuit High Voltage (NOx Sensor 2) code P11C0?

Possible causes include a faulty NOx sensor, damaged wiring or connectors in the O2 sensor circuit, or a problem with the engine control module (ECM).

3. How serious is the P11C0 fault code?

While the vehicle may still be drivable with this code, it is important to address it promptly to prevent potential damage to the engine or emissions system.

4. How can I diagnose and repair the P11C0 code?

Diagnosis typically involves checking the NOx sensor and associated wiring for damage, as well as testing the voltage in the O2 reference circuit. Repair may involve replacing the NOx sensor, repairing wiring, or reprogramming the ECM.

5. Can I drive my vehicle with the P11C0 code?

It is generally not recommended to drive your vehicle with an unresolved P11C0 code, as it may lead to further issues and potentially harm the engine or emissions system.

6. Will resetting the fault code make it go away permanently?

Resetting the code may temporarily turn off the check engine light, but if the underlying issue is not addressed, the code is likely to reappear during normal driving conditions.

7. How much does it typically cost to repair the P11C0 fault code?

The cost of repair can vary depending on the specific issue causing the code, but it may range from a couple of hundred to several hundred dollars, including parts and labor.

8. Can a DIY enthusiast fix the P11C0 code at home?

If you have the necessary tools and experience working on automotive systems, you may be able to diagnose and repair the P11C0 code yourself. However, it is recommended to consult a professional if you are unsure.

9. What happens if I ignore the P11C0 code?

Ignoring the P11C0 code may lead to reduced fuel efficiency, increased emissions, and potential long-term damage to the engine or emissions system.

10. How often does the O2 Reference Voltage Circuit High Voltage (NOx Sensor 2) code P11C0 occur?

The occurrence of this specific fault code can vary depending on the vehicle make and model, as well as driving conditions. If you encounter this code, it is essential to address it promptly to avoid further issues.