AutoCodes – Buick – U029E Buick

U029E Buick Code - Lost Communication with NOX Sensor Module 2 Malfunction

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 Nitrogen Oxide (NOx) Sensor Module 2, Nitrogen Oxide Sensor Module 2 harness is open or shorted, Nitrogen Oxide Sensor Module 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: U029E Buick indicates Lost Communication with NOX Sensor Module 2 Malfunction.
Common causes: Common causes include Faulty Nitrogen Oxide (NOx) Sensor Module 2, Nitrogen Oxide Sensor Module 2 harness is open or shorted, Nitrogen Oxide Sensor Module 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 765

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 Oct 18, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U029E Buick 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 U029E Buick - Lost Communication with NOX Sensor Module 2 Malfunction - AutoCodes.com — U029E Buick Code - Lost Communication with NOX Sensor Module 2 Malfunction

What does this mean?

What are the Possible Causes of the DTC U029E Buick?

Faulty Nitrogen Oxide (NOx) Sensor Module 2
Nitrogen Oxide Sensor Module 2 harness is open or shorted
Nitrogen Oxide Sensor Module 2 circuit poor electrical connection

How to Fix the DTC U029E Buick?

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 U029E Buick 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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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 U029E Buick Code

1. What are the common symptoms of OBDII code U029E in a Buick related to the NOX Sensor Module 2 malfunction?

The common symptoms include poor engine performance, reduced fuel efficiency, and potentially an illuminated check engine light.

2. What are the possible causes of the U029E code indicating a lost communication with the NOX Sensor Module 2 malfunction in a Buick?

Possible causes may include a faulty NOX sensor, damaged wiring or connectors, a malfunctioning NOX sensor module, or issues with the vehicle's computer system.

3. How can I diagnose the U029E code related to the NOX Sensor Module 2 malfunction in my Buick?

Diagnosis typically involves using a specialized OBDII scanner to retrieve the specific trouble code, visually inspecting the sensor and its connections for any visible damage, and conducting further electrical testing if needed.

4. Can I continue driving my Buick with the U029E code indicating a NOX Sensor Module 2 malfunction?

It is not recommended to continue driving your vehicle with this code present, as it can lead to further damage and potential safety hazards. It's best to have the issue diagnosed and repaired promptly.

5. Is it possible to reset the U029E code related to the NOX Sensor Module 2 malfunction in a Buick?

While you can clear the code using an OBDII scanner, it is essential to address the underlying issue causing the code to prevent it from reoccurring.

6. How much does it typically cost to repair the U029E code signaling a lost communication with the NOX Sensor Module 2 in a Buick?

The cost of repair can vary depending on the exact cause of the issue. It may range from a simple sensor replacement to more complex wiring or module repairs, so it's recommended to consult a mechanic for an accurate estimate.

7. Are there any DIY fixes I can try for the U029E code related to the NOX Sensor Module 2 malfunction in my Buick?

If you have experience with automotive repairs, you may attempt checking and cleaning the sensor connections or replacing the sensor yourself. However, for more complex issues, it's best to seek professional help.

8. How long does it typically take to repair the U029E code associated with the NOX Sensor Module 2 malfunction in a Buick?

The repair time can vary based on the exact cause and the extent of the issue. Simple fixes like sensor replacement may take less time, while more complex diagnoses and repairs can require more labor hours.

9. Can a U029E code indicating a NOX Sensor Module 2 malfunction affect my Buick's emissions or cause it to fail an emissions test?

Yes, a malfunctioning NOX sensor module can impact your vehicle's emissions output, potentially causing it to fail an emissions test. It's crucial to address the issue promptly to ensure your vehicle meets emissions standards.

10. Is the U029E code related to the NOX Sensor Module 2 malfunction a common issue in Buick vehicles?

While it may not be as common as some other OBDII codes, issues with the NOX sensor module can occur in Buick vehicles, especially as they age. Regular maintenance and prompt repairs can help prevent such problems.