AutoCodes – GMC – P119A 2017 GMC Sierra

P119A 2017 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 2017 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 162

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 Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P119A 2017 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 2017 GMC Sierra - NOx Sensor 1 Signal Circuit - AutoCodes.com — P119A 2017 GMC Sierra Code - NOx Sensor 1 Signal Circuit

What does this mean?

What are the Possible Causes of the DTC P119A 2017 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 2017 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 2017 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 2017 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 2017 GMC Sierra Code

1. What does the OBDII code P119A mean on a 2017 GMC Sierra?

P119A indicates an issue with the NOx Sensor 1 Signal Circuit, which monitors nitrogen oxide levels in the exhaust to ensure proper emissions control.

2. What are the common symptoms of code P119A on a GMC Sierra?

Common symptoms include the Check Engine Light turning on, reduced fuel efficiency, poor engine performance, and possible limp mode activation.

3. What causes the P119A code to appear on a 2017 GMC Sierra?

This code can be triggered by a faulty NOx sensor, damaged wiring or connectors, excessive soot buildup on the sensor, or an issue with the vehicleâ€™s ECM.

4. Can a dirty or faulty NOx sensor cause the P119A code?

Yes, a dirty or malfunctioning NOx sensor can cause inaccurate readings, triggering the P119A code.

5. How do you diagnose the P119A trouble code on a GMC Sierra?

Diagnosis involves scanning for codes with an OBDII scanner, visually inspecting the NOx sensor and wiring, testing the sensor with a multimeter, and checking for soot buildup or exhaust leaks.

6. Can I drive my 2017 GMC Sierra with the P119A code?

Driving with this code is not recommended, as it may lead to increased emissions, reduced fuel efficiency, or further damage to the emissions system.

7. How do you fix the P119A code on a GMC Sierra?

Common fixes include replacing the faulty NOx sensor, repairing damaged wiring or connectors, cleaning the sensor, or updating/reprogramming the ECM if needed.

8. How much does it cost to repair a P119A code on a 2017 GMC Sierra?

Repair costs vary but typically range from $300 to $800, depending on whether the NOx sensor needs replacement, cleaning, or wiring repair.

9. Can a software update resolve the P119A code?

In some cases, reprogramming or updating the ECM software may resolve the issue if the code is triggered by a software-related fault.

10. How can I prevent the P119A code from reoccurring?

Regular maintenance, using high-quality fuel, ensuring proper DEF fluid levels, and inspecting the exhaust system periodically can help prevent this code from reoccurring.