AutoCodes – GMC – P0402 2015 GMC Sierra

P0402 2015 GMC Sierra Code - Exhaust Gas Recirculation Flow Excessive

Quick Answer

The Exhaust Gas Recirculation (EGR) valve is controlled by the Engine Control Module (ECM). Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0402 2015 GMC Sierra indicates Exhaust Gas Recirculation Flow Excessive.
Common causes: Common causes include Faulty Exhaust Gas Recirculation (EGR) Valve, EGR solenoid valve harness is open or shorted, EGR solenoid valve circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 560

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 19, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0402 2015 GMC Sierra Description

The Exhaust Gas Recirculation (EGR) valve is controlled by the Engine Control Module (ECM). The ECM controls the EGR valve by supplying a 12-volt pulse width modulated signal to the EGR Valve low control circuit and 12 volts to the high control circuit. The ECM monitors the EGR flow performance when the EGR is active by comparing the desired Mass Air Flow (MAF) to the actual MAF. If the difference between the desired MAF and the actual MAF is less than or greater than a calibrated threshold level the amount of detected EGR flow is out of range. The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the difference between the desired mass air flow and the actual mass air flow is less than a calibrated value for greater than 12.5 s.

OBDII Code P0402 2015 GMC Sierra - Exhaust Gas Recirculation Flow Excessive - AutoCodes.com — P0402 2015 GMC Sierra Code - Exhaust Gas Recirculation Flow Excessive

What does this mean?

What are the Possible Causes of the DTC P0402 2015 GMC Sierra?

Faulty Exhaust Gas Recirculation (EGR) Valve
EGR solenoid valve harness is open or shorted
EGR solenoid valve circuit poor electrical connection

How to Fix the DTC P0402 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 P0402 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.

Need more information about the P0402 2015 GMC Sierra code?

Need more information on how to fix the P0402 2015 GMC Sierra code? Get Access to Factory Service Manuals

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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 P0402 2015 GMC Sierra Code

1. What does the OBDII code P0402 mean on a 2015 GMC Sierra?

P0402 indicates that the Exhaust Gas Recirculation (EGR) system is allowing excessive exhaust gas flow, which can disrupt engine performance.

2. What are the common symptoms of code P0402 on a 2015 GMC Sierra?

Symptoms include rough idling, reduced fuel efficiency, a check engine light, engine hesitation, or stalling.

3. What causes the P0402 code to appear on a 2015 GMC Sierra?

Common causes include a stuck-open EGR valve, clogged EGR passages, a malfunctioning EGR sensor, or a faulty EGR solenoid.

4. Can a dirty EGR valve trigger the P0402 code on a 2015 GMC Sierra?

Yes, carbon buildup can cause the EGR valve to stick open, leading to excessive exhaust gas flow.

5. Is it safe to drive with the P0402 code on a 2015 GMC Sierra?

While the vehicle may still be drivable, ignoring the issue can lead to poor engine performance, increased emissions, and potential long-term damage.

6. How can I fix the P0402 code on my 2015 GMC Sierra?

Start by cleaning the EGR valve and passages. If the issue persists, inspect and replace the EGR valve, sensor, or solenoid as needed.

7. Can a faulty EGR sensor cause the P0402 code on a 2015 GMC Sierra?

Yes, a malfunctioning EGR sensor may incorrectly signal excessive exhaust gas flow, triggering the code.

8. How much does it cost to repair the P0402 code on a 2015 GMC Sierra?

Repairs typically range from $150 to $400, depending on whether cleaning or replacing the EGR components is needed.

9. Can a vacuum leak cause the P0402 code on a 2015 GMC Sierra?

A vacuum leak is unlikely to directly cause P0402 but may contribute to improper EGR system function if affecting related components.

10. Will clearing the P0402 code fix the issue on a 2015 GMC Sierra?

Clearing the code will reset the check engine light temporarily, but the underlying issue must be addressed to prevent the code from returning.

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