AutoCodes – Jeep – U029D Jeep

U029D Jeep Code - Lost Communication With NOX Sensor 'A'

Quick Answer

The aftertreatment system is equipped with two NOx Sensors and modules. Common causes include Low Battery Voltage, Faulty Nitrogen Oxide (NOx) Sensor Bank 'A', Nitrogen Oxide (NOx) Sensor Bank 'A' harness is open or shorted. 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 Jeep indicates Lost Communication With NOX Sensor 'A'.
Common causes: Common causes include Low Battery Voltage, Faulty Nitrogen Oxide (NOx) Sensor Bank 'A', Nitrogen Oxide (NOx) Sensor Bank 'A' harness is open or shorted.
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 2,217

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 Apr 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U029D Jeep Description

The aftertreatment system is equipped with two NOx Sensors and modules. The upstream NOx Sensor 1/1 is located on the Turbocharger elbow downpipe and is permanently connected to a corresponding NOx Sensor Module mounted to the hot side of the engine block. The downstream NOx Sensor 1/2 is located at the outlet of the SCR Catalyst and is permanently connected to a corresponding NOx Sensor Module which is mounted on the right frame rail. The NOx Sensors and NOx Sensor Modules are calibrated to each other and must be replaced as an assembly. The two NOx Sensor and Module assemblies are not interchangeable. The NOx Sensor Modules are smart devices and communicate with the Powertrain Control Module (PCM) over the J1939 Data Link. The NOx Sensor Modules perform their own internal diagnostics and report malfunctions back to the PCM. The NOx Sensors are used to monitor the efficiency of the SCR Catalyst and dosing system. The PCM will illuminate the Malfunction Indicator Lamp (MIL) after the diagnostic runs and fails in two consecutive drive cycles. The PCM will turn off the MIL immediately after the monitor runs and passes.

OBDII Code U029D Jeep - Lost Communication With NOX Sensor 'A' - AutoCodes.com — U029D Jeep Code - Lost Communication With NOX Sensor 'A'

What does this mean?

What are the Possible Causes of the DTC U029D Jeep?

Low Battery Voltage
Faulty Nitrogen Oxide (NOx) Sensor Bank 'A'
Nitrogen Oxide (NOx) Sensor Bank 'A' harness is open or shorted
Nitrogen Oxide (NOx) Sensor Bank 'A' circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC U029D Jeep?

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 Jeep 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 U029D Jeep Code

1. What does the OBDII code U029D mean on a Jeep?

The U029D code indicates a "Lost Communication With NOx Sensor 'A'," meaning the vehicle's control module is not receiving data from the NOx sensor.

2. What are common symptoms of the U029D code on a Jeep?

Symptoms may include a check engine light, reduced engine performance, poor fuel efficiency, and in some cases, the vehicle entering limp mode.

3. What causes the U029D code to appear?

Common causes include a faulty NOx sensor, damaged wiring or connectors, a failed powertrain control module (PCM), or communication issues on the CAN bus network.

4. Can I drive my Jeep with the U029D code?

Driving with this code is possible, but itâ€™s not recommended as it may lead to reduced performance, increased emissions, and potential damage to the catalytic converter.

5. How do I diagnose the U029D code on my Jeep?

Diagnosis involves checking the NOx sensor and its wiring for damage, inspecting the CAN bus system for communication faults, and using a scan tool to monitor sensor data.

6. How do I fix the U029D code on a Jeep?

Repairs may include replacing the NOx sensor, repairing or replacing damaged wiring, fixing loose or corroded connectors, or reprogramming/updating the PCM.

7. How much does it cost to repair the U029D code on a Jeep?

Repair costs depend on the issue, but replacing a NOx sensor typically ranges from $300 to $700, including parts and labor.

8. What is the function of the NOx sensor in a Jeep?

The NOx sensor monitors nitrogen oxide levels in the exhaust to help the engine control module optimize emissions and meet environmental standards.

9. Can a software update fix the U029D code on a Jeep?

In some cases, a PCM software update can resolve communication issues if the problem is related to outdated programming.

10. How can I prevent the U029D code from recurring?

Regularly inspect and maintain the wiring and connections for the NOx sensor, and address any engine or exhaust issues promptly to prevent further damage.