AutoCodes – GMC – P119A 2018 GMC Sierra

P119A 2018 GMC Sierra Code - NOx Sensor 1 Signal Circuit

Quick Answer

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. Common causes include Faulty Nitrogen Oxides (NOx) Sensor, Nitrogen Oxides Sensor harness is open or shorted, Nitrogen Oxides Sensor 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: P119A 2018 GMC Sierra indicates NOx Sensor 1 Signal Circuit.
Common causes: Common causes include Faulty Nitrogen Oxides (NOx) Sensor, Nitrogen Oxides Sensor harness is open or shorted, Nitrogen Oxides Sensor 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 180

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 Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P119A 2018 GMC Sierra Description

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. There are two NOx sensors, one placed upstream of selective catalytic reduction, to measure inlet NOx concentration, and one placed downstream. They are connected with the control module via CAN and all the information is exchanged through it. Since it is a smart sensor, all the electrical monitoring is performed inside the sensor and only the results are sent to the Engine Control Module (ECM). 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 the 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 (reductant) added by varying the reductant injector duty cycle in response to changes in engine exhaust 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. The Diagnostic Trouble Code (DTC) will be set if the ECM software detects a fault in the NOx sensor circuitry or a performance fault in the NOx sensor for greater than 2 s.

OBDII Code P119A 2018 GMC Sierra - NOx Sensor 1 Signal Circuit - AutoCodes.com — P119A 2018 GMC Sierra Code - NOx Sensor 1 Signal Circuit

What does this mean?

What are the Possible Causes of the DTC P119A 2018 GMC Sierra?

Faulty Nitrogen Oxides (NOx) Sensor
Nitrogen Oxides Sensor harness is open or shorted
Nitrogen Oxides Sensor circuit poor electrical connection

How to Fix the DTC P119A 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 P119A 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.

Need more information about the P119A 2018 GMC Sierra code?

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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 P119A 2018 GMC Sierra Code

1. What does the OBDII code P119A mean on a 2018 GMC Sierra?

The code P119A indicates an issue with the NOx Sensor 1 Signal Circuit, which monitors nitrogen oxide emissions in the exhaust system.

2. What are common symptoms of code P119A in a 2018 GMC Sierra?

Symptoms may include a check engine light, reduced engine performance, increased fuel consumption, or failure to meet emissions standards.

3. What causes the P119A code on a 2018 GMC Sierra?

Common causes include a faulty NOx sensor, damaged wiring or connectors in the signal circuit, or issues with the engine control module (ECM).

4. Can I drive my 2018 GMC Sierra with the P119A code?

While the vehicle may still be drivable, it is not recommended, as prolonged operation can lead to increased emissions and potential damage to other components.

5. How do I diagnose the P119A code on a 2018 GMC Sierra?

Diagnosis typically involves scanning for additional codes, inspecting the NOx sensor and its wiring, and testing the sensor's functionality with a multimeter or diagnostic tool.

6. How do I fix the P119A code in a 2018 GMC Sierra?

Repairs may include replacing the NOx sensor, repairing or replacing damaged wiring or connectors, or reprogramming the ECM if necessary.

7. How much does it cost to fix the P119A code on a 2018 GMC Sierra?

The cost can range from $200 to $700, depending on whether the issue is with the NOx sensor, wiring, or ECM.

8. Can a bad NOx sensor cause other problems in my 2018 GMC Sierra?

Yes, a faulty NOx sensor can lead to poor engine performance, reduced fuel efficiency, and potential damage to the catalytic converter.

9. How can I prevent the P119A code from appearing on my 2018 GMC Sierra?

Regular maintenance, including inspecting the exhaust system and sensors, can help prevent issues with the NOx sensor signal circuit.

10. Does the P119A code require professional repair, or can I fix it myself?

If you have experience with automotive diagnostics and repairs, you may be able to fix it yourself, but professional assistance is recommended for accurate diagnosis and repair.