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P119A Chevrolet 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 Chevrolet 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 737
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 29, 2024
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Code P119A Chevrolet 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 Chevrolet - NOx Sensor 1 Signal Circuit - AutoCodes.com
P119A Chevrolet Code - NOx Sensor 1 Signal Circuit
What does this mean?

What are the Possible Causes of the DTC P119A Chevrolet?

  • 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 Chevrolet?

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 Chevrolet 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 Chevrolet code?

Need more information on how to fix the P119A Chevrolet code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Chevrolet Models

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 Chevrolet Code

1. What does the OBDII code P119A mean on a Chevrolet?

P119A indicates an issue with the signal circuit of NOx Sensor 1, which monitors nitrogen oxide levels in the exhaust system to ensure proper emissions control.

2. What are the common symptoms of a P119A code in a Chevrolet?

Symptoms may include the check engine light turning on, decreased fuel efficiency, poor engine performance, and possible failure to pass emissions tests.

3. What causes a P119A code to appear on a Chevrolet?

Common causes include a faulty NOx Sensor 1, wiring or connector issues in the NOx sensor circuit, or a malfunctioning engine control module (ECM).

4. How do I diagnose a P119A code on my Chevrolet?

Start by inspecting the NOx Sensor 1 wiring and connectors for damage or corrosion, then use an OBDII scanner to confirm the fault. A multimeter can test the sensor's signal circuit.

5. Can I drive my Chevrolet with a P119A code?

While the vehicle may still be drivable, operating with this code can lead to increased emissions, reduced fuel efficiency, and potential damage to the catalytic converter.

6. How can I fix the P119A code on a Chevrolet?

Repairs may include replacing the NOx Sensor 1, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the ECM if necessary.

7. How much does it cost to repair a P119A code on a Chevrolet?

Repair costs vary but typically range from $300 to $600 for sensor replacement, depending on the vehicle model and labor costs.

8. Can a dirty or clogged exhaust system cause a P119A code?

Yes, a clogged exhaust system can affect the NOx sensor's readings and trigger the code, though this is less common than sensor or wiring issues.

9. Does a P119A code require immediate attention?

Yes, addressing the issue promptly is recommended to avoid further damage to the emissions system and ensure compliance with emissions standards.

10. Do I need to reset the OBDII system after fixing a P119A code?

Yes, after repairs, clear the code with an OBDII scanner and perform a drive cycle to ensure the issue is resolved and the code does not reappear.

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