AutoCodes – Generic – P2BAB

P2BAB Code - NOx Exceedance - Incorrect EGR Flow

Quick Answer

The selective catalytic reduction system reduces oxides of nitrogen (NOx) emissions by injecting a metered amount of diesel exhaust fluid or reductant into the exhaust gas stream entering the diesel particulate filter (DPF). Common causes include Faulty NOx Sensors, NOx Sensors harness is open or shorted, NOx Sensors 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: P2BAB indicates NOx Exceedance - Incorrect EGR Flow.
Common causes: Common causes include Faulty NOx Sensors, NOx Sensors harness is open or shorted, NOx Sensors 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 31,519

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 Sep 01, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2BAB Description

The selective catalytic reduction system reduces oxides of nitrogen (NOx) emissions by injecting a metered amount of diesel exhaust fluid or reductant into the exhaust gas stream entering the diesel particulate filter (DPF). Within the selective catalytic reduction catalyst, the reductant reacts with the NOx to form nitrogen, carbon dioxide, and water vapor. Upstream and downstream NOx sensors provide the Engine Control Module (ECM) with engine-out and tailpipe-out NOx levels.
The ECM uses the 2 NOx sensors to control exhaust NOx levels. The NOx sensor measures the amount of NOx and oxygen in the exhaust system. The first NOx sensor is located at the outlet of the turbocharger and monitors the engine out NOx. The second NOx sensor is located in the DPF that monitors NOx levels exiting the DPF. The ECM varies the amount of reductant added by varying the reductant injector duty cycle in response to changes in engine exhaust out NOx levels.

OBDII Code P2BAB - NOx Exceedance - Incorrect EGR Flow - AutoCodes.com — P2BAB Code - NOx Exceedance - Incorrect EGR Flow

What does this mean?

What are the Possible Causes of the DTC P2BAB?

Faulty NOx Sensors
NOx Sensors harness is open or shorted
NOx Sensors circuit poor electrical connection
Fualty Diesel Particulate Filter (DPF)

How to Fix the DTC P2BAB?

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 P2BAB 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 P2BAB code?

Need more information on how to fix the P2BAB code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P2BAB code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P2BAB Chevrolet — NOx Exceedance - Incorrect EGR Flow
P2BAB Dodge — NOx Exceedance - Incorrect EGR Flow
P2BAB GMC — NOx Exceedance - Incorrect EGR Flow
P2BAB Toyota — NOx Emissions Exceeded Incorrect EGR Flow

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 P2BAB Code

1. What are common symptoms of OBDII code P2BAB (NOx Exceedance - Incorrect EGR Flow)?

Symptoms may include rough idling, decreased engine performance, and the illumination of the check engine light.

2. What can cause the OBDII code P2BAB to trigger?

The code is often triggered by issues such as a faulty EGR valve, clogged EGR passages, or problems with the EGR system sensors.

3. How can I diagnose the cause of OBDII code P2BAB?

Diagnosis typically involves checking the EGR valve functionality, inspecting EGR system components for blockages, and testing EGR system sensors for proper operation.

4. What are the potential effects of ignoring OBDII code P2BAB?

Continued driving with this code present can lead to increased emissions, reduced fuel efficiency, and potential damage to the catalytic converter.

5. Can I drive my vehicle with OBDII code P2BAB active?

It is not recommended to drive with this code active, as it can negatively impact engine performance and emissions levels.

6. How can I repair OBDII code P2BAB (NOx Exceedance - Incorrect EGR Flow)?

Repair may involve cleaning or replacing the EGR valve, clearing any blockages in the EGR system, or addressing sensor malfunctions within the EGR system.

7. Is it possible to reset OBDII code P2BAB without fixing the underlying issue?

While clearing the code may temporarily turn off the check engine light, the issue causing the code will likely persist and trigger the code again in the future.

8. Can a DIY enthusiast fix OBDII code P2BAB at home?

Depending on the specific cause, some individuals with automotive knowledge and tools may be able to address the issue themselves, particularly if it involves basic maintenance tasks like cleaning components.

9. How long does it typically take to repair OBDII code P2BAB?

The repair time can vary based on the cause of the code and the complexity of the necessary fixes, ranging from a quick sensor replacement to a more involved EGR system overhaul.

10. Are there any preventive measures to avoid OBDII code P2BAB in the future?

Regular maintenance of the EGR system, including cleaning components and ensuring proper sensor function, can help prevent issues that lead to the triggering of this code.