AutoCodes – Chevrolet – U029D Chevrolet

U029D Chevrolet Code - Lost Communication with NOX Sensor Module 1 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 1, Nitrogen Oxide Sensor Module 1 harness is open or shorted, Nitrogen Oxide Sensor Module 1 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: U029D Chevrolet indicates Lost Communication with NOX Sensor Module 1 Malfunction.
Common causes: Common causes include Faulty Nitrogen Oxide (NOx) Sensor Module 1, Nitrogen Oxide Sensor Module 1 harness is open or shorted, Nitrogen Oxide Sensor Module 1 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 5,002

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 U029D Chevrolet 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 U029D Chevrolet - Lost Communication with NOX Sensor Module 1 Malfunction - AutoCodes.com — U029D Chevrolet Code - Lost Communication with NOX Sensor Module 1 Malfunction

What does this mean?

What are the Possible Causes of the DTC U029D Chevrolet?

Faulty Nitrogen Oxide (NOx) Sensor Module 1
Nitrogen Oxide Sensor Module 1 harness is open or shorted
Nitrogen Oxide Sensor Module 1 circuit poor electrical connection

How to Fix the DTC U029D Chevrolet?

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 U029D Chevrolet 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 U029D Chevrolet code?

Need more information on how to fix the U029D Chevrolet code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Chevrolet Models

U029D 2014 Chevrolet Silverado — Lost Communication with NOX Sensor Module 1 Malfunction
U029D 2015 Chevrolet Silverado — Lost Communication with NOX Sensor Module 1 Malfunction
U029D 2016 Chevrolet Silverado — Lost Communication with NOX Sensor Module 1 Malfunction
U029D 2017 Chevrolet Silverado — Lost Communication with NOX Sensor Module 1 Malfunction
U029D 2018 Chevrolet Silverado — Lost Communication with NOX Sensor Module 1 Malfunction

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 U029D Chevrolet Code

1. What are the common symptoms of OBDII code U029D in a Chevrolet related to the NOX Sensor Module 1?

- Common symptoms include poor engine performance, reduced fuel efficiency, and the illumination of the Check Engine Light.

2. What can cause the U029D code indicating a Lost Communication with NOX Sensor Module 1 malfunction in a Chevrolet?

- The code U029D can be triggered by issues such as damaged wiring, a faulty NOX sensor, a defective NOX sensor module, or a communication error within the vehicle's network.

3. How can I diagnose the U029D code in a Chevrolet that points to a problem with the NOX Sensor Module 1?

- Diagnostic steps involve checking the wiring for any damage, testing the NOX sensor and module for functionality, and using a scan tool to identify communication errors within the vehicle's system.

4. Is it safe to continue driving my Chevrolet with the U029D code related to the NOX Sensor Module 1 issue?

- It is not recommended to drive your vehicle with the U029D code present, as it can lead to further damage and potentially affect the engine's performance and emissions.

5. Can I reset the U029D code on my Chevrolet indicating a Lost Communication with NOX Sensor Module 1 issue by disconnecting the battery?

- While disconnecting the battery may temporarily clear the code, it is important to address the underlying issue causing the code to prevent it from reoccurring.

6. How much does it typically cost to repair the U029D code related to the NOX Sensor Module 1 malfunction in a Chevrolet?

- The cost of repair can vary depending on the exact cause of the issue, but it may involve replacing the NOX sensor, module, or addressing wiring issues. Costs can range from $200 to $600 or more.

7. Are there any DIY repair tips for addressing the U029D code linked to the NOX Sensor Module 1 problem in a Chevrolet?

- DIY enthusiasts can start by checking the wiring connections for any visible damage and ensuring proper connections. However, diagnosing and repairing this code may require specialized tools and expertise.

8. Can a U029D code in a Chevrolet be related to other issues besides the NOX Sensor Module 1 malfunction?

- While the U029D code specifically points to a communication problem with the NOX Sensor Module 1, it is essential to address any underlying issues that may contribute to the malfunction, such as sensor failures or wiring issues.

9. How long does it typically take to repair the U029D code indicating a Lost Communication with NOX Sensor Module 1 in a Chevrolet?

- The repair time can vary depending on the exact cause of the issue and the availability of parts. In some cases, repairs can be completed within a few hours, while more complex issues may take longer.

10. Can a U029D code related to the NOX Sensor Module 1 malfunction affect the vehicle's emissions and cause it to fail an emissions test?

- Yes, the U029D code indicating a problem with the NOX Sensor Module 1 can impact the vehicle's emissions, potentially causing it to fail an emissions test. It is crucial to address this issue promptly to ensure compliance with emissions regulations.