AutoCodes – Generic – P11B4

P11B4 Code - HO2S Current Performance Bank 1 Sensor 1

Quick Answer

The reductant system uses two Nitrogen Oxide (NOx) sensors to monitor the amount of NOx in the engine's exhaust gas. Common causes include Faulty Heated Oxygen Sensor (HO2S), Heated Oxygen Sensor (HO2S) harness is open or shorted, Heated Oxygen Sensor (HO2S) 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: P11B4 indicates HO2S Current Performance Bank 1 Sensor 1.
Common causes: Common causes include Faulty Heated Oxygen Sensor (HO2S), Heated Oxygen Sensor (HO2S) harness is open or shorted, Heated Oxygen Sensor (HO2S) 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 12,232

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 Aug 28, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P11B4 Description

The reductant system uses two Nitrogen Oxide (NOx) sensors to monitor the amount of NOx in the engine's exhaust gas. The first sensor is located at the outlet of the turbocharger and monitors the engine out NOx level. The second NOx sensor is located between the Selective Catalytic Reduction (SCR) and the Diesel Particulate Filter (DPF) and monitors NOx levels downstream of the SCR. The second NOx sensor also provides the Engine Control Module (ECM) with information on the exhaust oxygen level during DPF regeneration.
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 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 (DEF) or reductant added by varying the reductant injector duty cycle in response to changes in engine exhaust out 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.

OBDII Code P11B4 - HO2S Current Performance Bank 1 Sensor 1 - AutoCodes.com — P11B4 Code - HO2S Current Performance Bank 1 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P11B4?

Faulty Heated Oxygen Sensor (HO2S)
Heated Oxygen Sensor (HO2S) harness is open or shorted
Heated Oxygen Sensor (HO2S) circuit poor electrical connection

How to Fix the DTC P11B4?

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 P11B4 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 P11B4 code?

Need more information on how to fix the P11B4 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P11B4 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P11B4 Chevrolet — HO2S Current Performance Bank 1 Sensor 1
P11B4 GMC — HO2S Current Performance Bank 1 Sensor 1

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 P11B4 Code

1. What are the common symptoms of OBDII code P11B4?

The common symptoms of OBDII code P11B4, HO2S Current Performance Bank 1 Sensor 1, include poor fuel efficiency, rough idling, and an illuminated check engine light.

2. What could cause the OBDII code P11B4 to be triggered?

The OBDII code P11B4 can be triggered by issues such as a faulty oxygen sensor, exhaust leaks, wiring problems, or a malfunctioning engine control module (ECM).

3. How can I diagnose the cause of the OBDII code P11B4?

To diagnose the cause of the OBDII code P11B4, it's recommended to perform a thorough inspection of the oxygen sensor, check for exhaust leaks, test the wiring connections, and use a scan tool to monitor sensor data.

4. Can a dirty or contaminated oxygen sensor cause the OBDII code P11B4?

Yes, a dirty or contaminated oxygen sensor can contribute to the triggering of the OBDII code P11B4, as it may not accurately measure the air-fuel ratio in the exhaust system.

5. What are some repair tips for addressing the OBDII code P11B4?

Repair tips for addressing the OBDII code P11B4 include cleaning or replacing the oxygen sensor, repairing any exhaust leaks, checking and repairing wiring issues, and resetting the ECM.

6. How important is it to address the OBDII code P11B4 promptly?

It is important to address the OBDII code P11B4 promptly to prevent potential damage to the catalytic converter, ensure optimal engine performance, and maintain fuel efficiency.

7. Can driving with the OBDII code P11B4 cause further damage to the vehicle?

Continued driving with the OBDII code P11B4 may lead to decreased fuel efficiency, engine misfires, and potential damage to the catalytic converter, so it's best to address the issue promptly.

8. How can I prevent the OBDII code P11B4 from reoccurring?

To prevent the OBDII code P11B4 from reoccurring, it's essential to perform regular maintenance on the oxygen sensor, address any exhaust system leaks promptly, and ensure proper wiring connections.

9. Is it possible to clear the OBDII code P11B4 without fixing the underlying issue?

Clearing the OBDII code P11B4 without fixing the underlying issue may temporarily turn off the check engine light, but the problem will likely reoccur, so it's best to address the root cause of the code.

10. Can I fix the OBDII code P11B4 myself, or should I seek professional help?

Depending on your automotive experience and tools available, you may be able to address the OBDII code P11B4 yourself by following diagnostic procedures and repair steps. However, seeking professional help from a certified mechanic is recommended for accurate diagnosis and repair.