U029D 2018 GMC Sierra 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 2018 GMC Sierra 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.
Code U029D 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 U029D 2018 GMC Sierra?
- 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 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 U029D 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 U029D 2018 GMC Sierra Code
1. What does the OBDII code U029D mean on a 2018 GMC Sierra?
The U029D code indicates a loss of communication between the vehicle’s control module and NOx Sensor Module 1, which monitors nitrogen oxide levels in the exhaust.
2. What are the common symptoms of the U029D code on a 2018 GMC Sierra?
Symptoms may include the check engine light turning on, reduced engine performance, increased emissions, and, in some cases, poor fuel efficiency.
3. What causes the U029D code to appear on a 2018 GMC Sierra?
Common causes include a faulty NOx sensor, damaged wiring or connectors, a failed sensor module, or communication issues within the vehicle’s network.
4. Can driving with the U029D code damage my 2018 GMC Sierra?
While the vehicle may still operate, ignoring this code can lead to poor emissions performance, potential damage to the catalytic converter, or problems with the diesel exhaust system.
5. How do I diagnose the U029D code on a 2018 GMC Sierra?
Start by checking the wiring and connectors for the NOx sensor. Then use a scan tool to verify the communication status and test the functionality of the NOx Sensor Module 1.
6. Can a software issue cause the U029D code on a 2018 GMC Sierra?
Yes, outdated or corrupted software in the vehicle’s control module can sometimes cause communication errors like the U029D code.
7. How do I fix the U029D code on a 2018 GMC Sierra?
Repairs may involve replacing the NOx sensor, repairing damaged wiring or connectors, updating vehicle software, or replacing the sensor module if it’s faulty.
8. Is the U029D code covered under warranty for a 2018 GMC Sierra?
It depends on your vehicle’s warranty terms. Emissions-related components often have extended coverage, so check with your GMC dealer.
9. How much does it cost to repair the U029D code on a 2018 GMC Sierra?
Repair costs vary but can range from $200-$600, depending on whether the issue is with the sensor, wiring, or module.
10. Can a dirty or clogged exhaust system trigger the U029D code?
While less common, excessive soot buildup or exhaust blockages can sometimes lead to sensor communication issues or false readings.
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