AutoCodes – GMC – P0402 2016 GMC Sierra

P0402 2016 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 2016 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 506

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 2016 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 2016 GMC Sierra - Exhaust Gas Recirculation Flow Excessive - AutoCodes.com — P0402 2016 GMC Sierra Code - Exhaust Gas Recirculation Flow Excessive

What does this mean?

What are the Possible Causes of the DTC P0402 2016 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 2016 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 2016 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 P0402 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code P0402 (Exhaust Gas Recirculation Flow Excessive) in a 2016 GMC Sierra?

Excessive exhaust smoke, rough idle, engine hesitation, and decreased fuel efficiency are common symptoms of code P0402 in a GMC Sierra.

2. What are the possible causes of OBDII code P0402 in a 2016 GMC Sierra?

Potential causes of code P0402 in a GMC Sierra include a faulty EGR valve, clogged EGR passages, wiring issues, or a malfunctioning EGR temperature sensor.

3. How can I diagnose OBDII code P0402 in my 2016 GMC Sierra?

Diagnosing code P0402 involves checking the EGR valve operation, inspecting EGR system components for blockages, testing the EGR temperature sensor, and scanning for any related trouble codes.

4. Can a dirty or clogged EGR valve trigger code P0402 in a 2016 GMC Sierra?

Yes, a dirty or clogged EGR valve can restrict exhaust gas flow, leading to excessive EGR flow and triggering code P0402 in a GMC Sierra.

5. What is the recommended repair approach for OBDII code P0402 in a 2016 GMC Sierra?

Repairing code P0402 typically involves cleaning or replacing the EGR valve, clearing any blockages in the EGR system, checking and repairing wiring connections, and resetting the fault code.

6. Is it safe to drive my 2016 GMC Sierra with OBDII code P0402 active?

While the vehicle may still be operable with code P0402, it is recommended to address the issue promptly to prevent further damage and maintain optimal engine performance.

7. Can a malfunctioning EGR temperature sensor cause code P0402 in a 2016 GMC Sierra?

Yes, a faulty EGR temperature sensor can provide incorrect data to the engine control module, leading to improper EGR flow and triggering OBDII code P0402.

8. Will resetting the OBDII code P0402 in my 2016 GMC Sierra make the issue go away?

Simply clearing the fault code without addressing the underlying cause will not fix the problem. It is crucial to diagnose and repair the root issue triggering code P0402.

9. Are there any maintenance tips to prevent OBDII code P0402 in a 2016 GMC Sierra?

Regularly servicing the EGR system, using quality fuel, and ensuring timely engine maintenance can help prevent issues like code P0402 in a GMC Sierra.

10. How long does it typically take to repair OBDII code P0402 in a 2016 GMC Sierra?

The repair time for code P0402 can vary based on the exact cause and extent of the issue. Simple fixes like cleaning the EGR valve may take less time, while more complex repairs could require additional labor.