AutoCodes – GMC – U029E GMC

U029E GMC 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 GMC 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 3,319

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 GMC 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 GMC - Lost Communication with NOX Sensor Module 2 Malfunction - AutoCodes.com — U029E GMC Code - Lost Communication with NOX Sensor Module 2 Malfunction

What does this mean?

What are the Possible Causes of the DTC U029E GMC?

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 GMC?

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 GMC 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 U029E GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

U029E 2014 GMC Sierra — Lost Communication with NOX Sensor Module 2 Malfunction
U029E 2015 GMC Sierra — Lost Communication with NOX Sensor Module 2 Malfunction
U029E 2016 GMC Sierra — Lost Communication with NOX Sensor Module 2 Malfunction
U029E 2017 GMC Sierra — Lost Communication with NOX Sensor Module 2 Malfunction
U029E 2018 GMC Sierra — Lost Communication with NOX Sensor Module 2 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 U029E GMC Code

1. What are common symptoms of the U029E GMC OBDII code related to Lost Communication with NOX Sensor Module 2 Malfunction?

Common symptoms include the Check Engine Light illuminating, poor engine performance, decreased fuel efficiency, and potential issues with emissions.

2. What are the possible causes of the U029E GMC code indicating Lost Communication with NOX Sensor Module 2 Malfunction?

Potential causes may include a faulty NOX sensor module, damaged wiring or connections, software issues, or a malfunctioning Engine Control Module (ECM).

3. How can I diagnose the U029E GMC code for Lost Communication with NOX Sensor Module 2 Malfunction?

Diagnosis typically involves using an OBDII scanner to retrieve the code, checking the NOX sensor module and associated wiring for damage, and performing a thorough inspection of the ECM and related components.

4. How can I repair the U029E GMC code for Lost Communication with NOX Sensor Module 2 Malfunction?

Repair may involve replacing the NOX sensor module, repairing or replacing damaged wiring or connections, updating software as needed, or replacing the ECM if deemed faulty.

5. Can I continue driving my vehicle with the U029E GMC code for Lost Communication with NOX Sensor Module 2 Malfunction?

It is not recommended to drive with this code present, as it can lead to further damage and potential safety issues. It is best to address the underlying problem promptly.

6. Are there any DIY tips for resolving the U029E GMC OBDII code related to Lost Communication with NOX Sensor Module 2 Malfunction?

While some basic checks like inspecting connections and wiring can be done DIY, dealing with NOX sensor modules and ECM issues may require advanced automotive knowledge or professional assistance.

7. How much does it typically cost to repair the U029E GMC code for Lost Communication with NOX Sensor Module 2 Malfunction?

The cost of repair can vary depending on the specific cause of the issue, parts needed, labor rates, and whether you choose to address it yourself or take it to a mechanic. It's advisable to get multiple quotes for an accurate estimate.

8. Can a faulty NOX sensor module cause other problems in addition to the U029E GMC code?

Yes, a malfunctioning NOX sensor module can impact engine performance, emissions levels, and overall vehicle efficiency. Addressing the issue promptly can prevent further complications.

9. How long does it typically take to repair the U029E GMC code related to Lost Communication with NOX Sensor Module 2 Malfunction?

The repair time can vary depending on the complexity of the issue, availability of parts, and the expertise of the technician. It's best to consult with a professional for a more accurate timeframe.

10. Is the U029E GMC code for Lost Communication with NOX Sensor Module 2 Malfunction a common issue in GMC vehicles?

While not as common as some other OBDII codes, issues related to NOX sensor modules and communication can occur in GMC vehicles, particularly in models equipped with advanced emissions control systems.