U029E 2018 GMC Sierra 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 2018 GMC Sierra 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.
Code U029E 2018 GMC Sierra Description
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.
What are the Possible Causes of the DTC U029E 2018 GMC Sierra?
- 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 2018 GMC Sierra?
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 2018 GMC Sierra 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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Frequently Asked Questions about U029E 2018 GMC Sierra Code
1. What does the OBDII code U029E mean on a 2018 GMC Sierra?
U029E indicates a "Lost Communication with NOx Sensor Module 2," meaning the engine control module (ECM) cannot communicate with the second NOx sensor module.
2. What are the symptoms of the U029E code on a GMC Sierra?
Common symptoms include an illuminated check engine light, reduced engine performance, increased emissions, and possibly the truck entering limp mode.
3. What causes the U029E code to appear?
The most common causes are a faulty NOx sensor module, damaged wiring or connectors, issues with the CAN (Controller Area Network) bus communication, or a failing ECM.
4. Can a faulty NOx sensor cause drivability issues?
Yes, a faulty NOx sensor can cause reduced engine performance, poor fuel economy, and the vehicle entering limp mode to protect the engine.
5. How can I diagnose the U029E code on my 2018 GMC Sierra?
Start by checking the wiring and connectors of the NOx sensor module for damage or corrosion. Use an advanced OBDII scanner to check for additional trouble codes and verify communication with the sensor.
6. Is the U029E code specific to NOx Sensor Module 2?
Yes, the U029E code specifically references a communication issue with NOx Sensor Module 2, which is typically located downstream in the exhaust system.
7. Can I drive my GMC Sierra with the U029E code?
It’s not recommended to drive for an extended period as the code may lead to reduced performance, higher emissions, and potential damage to the emissions system.
8. How much does it cost to fix the U029E code?
Repair costs vary depending on the issue. Replacing a NOx sensor can cost $300-$700, while wiring repairs or ECM issues may raise costs significantly.
9. Can a software update fix the U029E code?
In some cases, a software update for the ECM may resolve communication issues, but this depends on the root cause of the code.
10. What maintenance can prevent the U029E code from appearing?
Regularly inspect and maintain exhaust components, wiring, and connectors, and ensure the ECM software is up to date to prevent communication problems.
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