AutoCodes – GMC – P0402 2017 GMC Sierra

P0402 2017 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 2017 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 256

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 2017 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 2017 GMC Sierra - Exhaust Gas Recirculation Flow Excessive - AutoCodes.com — P0402 2017 GMC Sierra Code - Exhaust Gas Recirculation Flow Excessive

What does this mean?

What are the Possible Causes of the DTC P0402 2017 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 2017 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 2017 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 2017 GMC Sierra code?

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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 2017 GMC Sierra Code

1. What does the P0402 code mean for a 2017 GMC Sierra?

The P0402 code indicates that the Exhaust Gas Recirculation (EGR) system is detecting excessive exhaust gas flow into the intake manifold.

2. What are the common symptoms of the P0402 code in a 2017 GMC Sierra?

Symptoms can include a check engine light, rough idle, poor acceleration, decreased fuel efficiency, and possible engine stalling.

3. What causes the P0402 code to appear on a 2017 GMC Sierra?

Common causes include a stuck-open EGR valve, clogged EGR passages, a faulty EGR position sensor, or issues with the EGR control solenoid.

4. Can a dirty EGR valve cause the P0402 code on a 2017 GMC Sierra?

Yes, a dirty or carbon-clogged EGR valve can stick open, leading to excessive exhaust gas flow and triggering the P0402 code.

5. Is it safe to drive a 2017 GMC Sierra with a P0402 code?

Driving with this code is not recommended as it can lead to engine performance issues, higher emissions, and potential damage to other components.

6. How can the P0402 code on a 2017 GMC Sierra be diagnosed?

Diagnosis typically involves inspecting the EGR valve, checking for carbon deposits, testing the EGR position sensor, and ensuring proper operation of the EGR control solenoid.

7. What repairs can fix the P0402 code on a 2017 GMC Sierra?

Common fixes include cleaning or replacing the EGR valve, clearing clogged passages, repairing wiring to the EGR system, or replacing the EGR position sensor.

8. What tools are needed to troubleshoot the P0402 code on a 2017 GMC Sierra?

Tools include an OBDII scanner, a multimeter for electrical tests, and basic hand tools to remove and inspect the EGR valve.

9. Can a vacuum leak cause the P0402 code on a 2017 GMC Sierra?

While uncommon, a vacuum leak in systems related to the EGR can contribute to improper function, potentially causing the code.

10. How much does it cost to fix a P0402 code on a 2017 GMC Sierra?

Costs vary widely depending on the repair, ranging from $150 to $400 for cleaning or replacing the EGR valve, with additional costs for labor or sensor replacements.