AutoCodes – GMC – P119A GMC

P119A GMC 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 GMC 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 381

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 29, 2024

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

What does this mean?

What are the Possible Causes of the DTC P119A GMC?

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 GMC?

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 GMC 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 GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

P119A 2014 GMC Sierra — NOx Sensor 1 Signal Circuit
P119A 2015 GMC Sierra — NOx Sensor 1 Signal Circuit
P119A 2016 GMC Sierra — NOx Sensor 1 Signal Circuit
P119A 2017 GMC Sierra — NOx Sensor 1 Signal Circuit
P119A 2018 GMC Sierra — NOx Sensor 1 Signal Circuit

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 GMC Code

What does the OBDII code P119A mean on a GMC vehicle?

1. The P119A code indicates an issue with the signal circuit of NOx Sensor 1, which monitors nitrogen oxide levels in the exhaust system. 2.

What are the common symptoms of the P119A code in a GMC?

Symptoms may include reduced engine performance, increased fuel consumption, an illuminated check engine light, and possibly a failed emissions test. 3.

What causes the P119A code to appear?

The code can be caused by a faulty NOx Sensor 1, damaged wiring, a corroded connector, or issues with the Engine Control Module (ECM). 4.

Can I drive my GMC with the P119A code?

Driving with this code is not recommended as it can lead to poor fuel economy, increased emissions, and potential damage to the exhaust aftertreatment system. 5.

How do you diagnose the P119A code on a GMC?

Diagnosis typically involves scanning the ECM for codes, inspecting the NOx sensor and its wiring, and testing the sensor's functionality using a multimeter or scan tool. 6.

How do you fix the P119A code in a GMC vehicle?

Repairs may include replacing the NOx Sensor 1, repairing damaged wiring or connectors, and updating or reprogramming the ECM if needed. 7.

What tools are needed to address the P119A code?

Youâ€™ll need an OBDII scanner, a multimeter for electrical testing, and possibly specialized tools to remove and replace the NOx sensor. 8.

How much does it cost to fix the P119A code?

Repair costs can range from $200 to $800, depending on whether you need a new NOx sensor, wiring repairs, or ECM programming. 9.

Can a dirty diesel particulate filter (DPF) trigger the P119A code?

While the DPF itself is not directly related, excessive soot buildup can damage the NOx sensor or interfere with its readings, potentially triggering the code. 10.

Does a software update fix the P119A code in GMC vehicles?

In some cases, a software update for the ECM may resolve the issue, especially if the problem is related to inaccurate sensor calibration or programming errors.