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P1004 2017 GMC Sierra Code - NOx Sensor 2 Slow Response

Quick Answer

The P1004 diagnostic trouble code (DTC) for a 2017 GMC Sierra indicates a problem with the NOx (nitrogen oxide) sensor 2 slow response. Common causes include Faulty NOx Sensor: The most common cause of the P1004 code is a malfunctioning NOx sensor 2 that is not responding as quickly as it should, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the NOx sensor can also trigger this code, Exhaust Leaks: Leaks in the exhaust system, particularly near the NOx sensor, can lead to erroneous readings and trigger the P1004 code. 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
P1004 2017 GMC Sierra indicates NOx Sensor 2 Slow Response.
Common causes
Common causes include Faulty NOx Sensor: The most common cause of the P1004 code is a malfunctioning NOx sensor 2 that is not responding as quickly as it should, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the NOx sensor can also trigger this code, Exhaust Leaks: Leaks in the exhaust system, particularly near the NOx sensor, can lead to erroneous readings and trigger the P1004 code.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 11, 2024
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Code P1004 2017 GMC Sierra Description

The P1004 diagnostic trouble code (DTC) for a 2017 GMC Sierra indicates a problem with the NOx (nitrogen oxide) sensor 2 slow response. The NOx sensor is a crucial component in the vehicle's emissions control system, responsible for monitoring and measuring the levels of nitrogen oxides in the exhaust gases.

OBDII Code P1004 2017 GMC Sierra - NOx Sensor 2 Slow Response
P1004 2017 GMC Sierra Code - NOx Sensor 2 Slow Response

Common Causes of P1004 2017 GMC Sierra

  1. Faulty NOx Sensor: The most common cause of the P1004 code is a malfunctioning NOx sensor 2 that is not responding as quickly as it should.
  2. Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the NOx sensor can also trigger this code.
  3. Exhaust Leaks: Leaks in the exhaust system, particularly near the NOx sensor, can lead to erroneous readings and trigger the P1004 code.
  4. Catalytic Converter Problems: Issues with the catalytic converter, such as deterioration or contamination, can impact the performance of the NOx sensor and trigger this code.

Symptoms of P1004 2017 GMC Sierra

  1. Check Engine Light: The most common symptom associated with the P1004 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Fuel Efficiency: A slow response from the NOx sensor can lead to improper fuel mixture adjustments, resulting in decreased fuel efficiency.
  3. Failed Emissions Test: A malfunctioning NOx sensor can cause the vehicle to fail emissions tests due to inaccurate readings of nitrogen oxide levels.
  4. Rough Idling or Poor Engine Performance: The engine may exhibit rough idling, hesitation, or overall poor performance due to inaccurate sensor readings.

How to Fix P1004 2017 GMC Sierra

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific trouble code (P1004) and perform additional testing to pinpoint the exact cause of the NOx sensor 2 slow response.
  2. Replace the NOx Sensor: If the sensor is determined to be faulty, replace it with a new, OEM-quality sensor to ensure accurate readings and proper function.
  3. Check Wiring and Connections: Inspect the wiring harness for any damage, corrosion, or loose connections and repair or replace as needed.
  4. Repair Exhaust Leaks: Address any leaks in the exhaust system, particularly near the NOx sensor location, to prevent false readings and ensure proper sensor function.
  5. Test and Clear Codes: After completing the repairs, test the vehicle to ensure the issue has been resolved, and clear the trouble codes from the ECM using a diagnostic scanner.

Cost to Fix P1004 2017 GMC Sierra

The typical repair costs for addressing a NOx sensor 2 slow response issue can vary depending on the specific cause of the problem and the labor rates in your area. In general, replacing a faulty NOx sensor can cost anywhere from $200 to $500, including parts and labor. However, if additional repairs are needed, such as addressing wiring issues or exhaust leaks, the total cost could be higher.

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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 P1004 2017 GMC Sierra Code

1. What does the OBDII code P1004 mean on a 2017 GMC Sierra?

The P1004 code indicates a "NOx Sensor 2 Slow Response," meaning the downstream NOx sensor is not responding as expected to changes in exhaust gas composition.

2. What are the symptoms of the P1004 code?

Common symptoms include an illuminated check engine light, decreased fuel efficiency, potential power loss, and increased emissions.

3. What causes the P1004 code to appear?

The code can be caused by a faulty NOx sensor, wiring issues, exhaust leaks, soot buildup on the sensor, or a malfunctioning engine control module (ECM).

4. How can I diagnose the P1004 code on my GMC Sierra?

Start by inspecting the NOx sensor wiring for damage, checking for exhaust leaks, and using a scan tool to monitor the NOx sensor readings to see if they are within the expected range.

5. Can I drive my 2017 GMC Sierra with the P1004 code?

While the vehicle may still be drivable, it’s not recommended as it can lead to poor performance, increased emissions, and potential damage to the catalytic converter.

6. How do I fix the P1004 code on a 2017 GMC Sierra?

Repairs may include replacing the faulty NOx sensor, repairing damaged wiring, cleaning soot buildup, or addressing exhaust leaks. In some cases, the ECM may need reprogramming.

7. How much does it cost to fix the P1004 code?

Replacing a NOx sensor can cost between $300 and $800, depending on labor and parts. Additional repairs like fixing wiring or exhaust leaks can increase the cost.

8. Can a clogged DEF system cause the P1004 code?

Yes, a clogged Diesel Exhaust Fluid (DEF) injector or system can affect NOx sensor performance and contribute to this code.

9. How can I prevent the P1004 code from recurring?

Regularly maintain the exhaust and DEF systems, use high-quality DEF fluid, and address any engine performance issues promptly to prevent strain on the NOx sensors.

10. What is the difference between NOx Sensor 1 and NOx Sensor 2?

NOx Sensor 1 is located upstream of the SCR (Selective Catalytic Reduction) system, while NOx Sensor 2 is located downstream to monitor the effectiveness of the SCR in reducing NOx emissions.

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