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U029E Cadillac 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 Cadillac 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 648

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 Oct 18, 2022

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

What does this mean?

What are the Possible Causes of the DTC U029E Cadillac?

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 Cadillac?

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 Cadillac 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 Cadillac Code

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

The common symptoms include the check engine light illuminating, reduced engine performance, and potential issues with emissions compliance.

2. What are some possible causes of the U029E code in a Cadillac?

Possible causes include a faulty NOX sensor module, wiring or connection issues, a software glitch, or a problem with the vehicle's electronic control module (ECM).

3. How serious is the U029E code in a Cadillac?

While the code itself may not cause immediate harm to the vehicle, it can lead to increased emissions and potential performance issues if left unresolved. It is important to address the underlying issue promptly.

4. Can I continue driving my Cadillac with the U029E code present?

It is generally not recommended to continue driving the vehicle with the U029E code present, as it can affect the vehicle's performance and emissions. It is best to have the issue diagnosed and repaired as soon as possible.

5. How can I diagnose the U029E code in my Cadillac?

Diagnosing the U029E code typically involves using an OBDII scanner to retrieve the specific fault codes, inspecting the NOX sensor module and related wiring, and performing any necessary software updates.

6. Is it possible to repair the U029E code in a Cadillac myself?

While some DIY enthusiasts may be able to address simple wiring or connection issues, diagnosing and repairing the U029E code often requires specialized tools and expertise. It is recommended to consult a professional mechanic for proper diagnosis and repair.

7. How much does it cost to repair the U029E code in a Cadillac?

The cost of repairing the U029E code can vary depending on the underlying cause of the issue. It is recommended to obtain diagnostic information and repair estimates from a trusted mechanic.

8. Can resetting the fault codes clear the U029E code in a Cadillac?

Resetting the fault codes may temporarily clear the check engine light, but it will not solve the underlying issue causing the U029E code. It is important to diagnose and address the root cause of the problem.

9. What steps should I take if the U029E code keeps coming back in my Cadillac?

If the U029E code keeps coming back after clearing the fault codes, it is important to have a thorough diagnostic inspection performed to identify and resolve the underlying issue causing the code to reappear.

10. How can I prevent the U029E code from recurring in my Cadillac?

Regular maintenance, including checking and replacing sensors as needed, keeping the vehicle's software up to date, and addressing any electrical issues promptly, can help prevent the U029E code from recurring in your Cadillac.