AutoCodes – GMC – P1004 2015 GMC Sierra

P1004 2015 GMC Sierra Code - NOx Sensor 2 Slow Response

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 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides Sensor 2 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: P1004 2015 GMC Sierra indicates NOx Sensor 2 Slow Response.
Common causes: Common causes include Faulty Nitrogen Oxides (NOx) Sensor 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides Sensor 2 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 164

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
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Code P1004 2015 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 P1004 2015 GMC Sierra - NOx Sensor 2 Slow Response - AutoCodes.com — P1004 2015 GMC Sierra Code - NOx Sensor 2 Slow Response

What does this mean?

What are the Possible Causes of the DTC P1004 2015 GMC Sierra?

Faulty Nitrogen Oxides (NOx) Sensor 2
Nitrogen Oxides Sensor 2 harness is open or shorted
Nitrogen Oxides Sensor 2 circuit poor electrical connection

How to Fix the DTC P1004 2015 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 P1004 2015 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.

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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 2015 GMC Sierra Code

1. What does the OBDII code P1004 mean on a 2015 GMC Sierra?

P1004 indicates that the second NOx (nitrogen oxide) sensor has a slow response, meaning it is not operating as efficiently as expected.

2. What are the common symptoms of code P1004 on a 2015 GMC Sierra?

Symptoms may include the check engine light turning on, reduced fuel efficiency, increased emissions, and potential issues with the vehicle entering limp mode.

3. What causes the P1004 code on a 2015 GMC Sierra?

The most common causes include a faulty NOx sensor, wiring or connector issues, exhaust leaks, or a malfunctioning exhaust after-treatment system.

4. Can I drive my 2015 GMC Sierra with the P1004 code?

While the vehicle may still be drivable, ignoring this code can lead to increased emissions, reduced performance, and potential damage to the exhaust after-treatment system.

5. How do I diagnose the P1004 code on my GMC Sierra?

Diagnosis involves scanning with an OBDII scanner, inspecting the NOx sensor wiring and connectors, checking for exhaust leaks, and testing the sensor for proper operation.

6. How do I fix the P1004 code on a 2015 GMC Sierra?

Repairs may include replacing the NOx sensor, fixing any damaged wiring or connectors, repairing exhaust leaks, or updating the vehicleâ€™s engine control module (ECM software).

7. How much does it cost to repair the P1004 code on a GMC Sierra?

The cost depends on the specific issue, but replacing a NOx sensor typically ranges from $300 to $700, including parts and labor.

8. Can a bad NOx sensor damage my 2015 GMC Sierra?

A failing NOx sensor can lead to increased emissions and stress on the exhaust after-treatment system, potentially causing further damage if not addressed.

9. What tools do I need to diagnose the P1004 code?

Youâ€™ll need an OBDII scanner to read the code, a multimeter to test wiring, and possibly tools to inspect and repair the exhaust system.

10. Is the P1004 code covered under warranty for a 2015 GMC Sierra?

If your vehicle is still under warranty or covered by an emissions-related warranty, the repair may be covered. Check with your dealership for specific details.