AutoCodes – GMC – P0401 2016 GMC Sierra

P0401 2016 GMC Sierra Code - Exhaust Gas Recirculation Flow Insufficient

Quick Answer

The Exhaust Gas Recirculation (EGR) valve is controlled by the Engine Control Module (ECM). Common causes include Exhaust Gas Recirculation (EGR) passage clogged, Faulty EGR Valve, EGR solenoid valve harness is open or shorted. 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: P0401 2016 GMC Sierra indicates Exhaust Gas Recirculation Flow Insufficient.
Common causes: Common causes include Exhaust Gas Recirculation (EGR) passage clogged, Faulty EGR Valve, EGR solenoid valve harness is open or shorted.
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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 338

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
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0401 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 airflow and the actual mass air flow is less than a calibrated value for greater than 12.5 s.

OBDII Code P0401 2016 GMC Sierra - Exhaust Gas Recirculation Flow Insufficient - AutoCodes.com — P0401 2016 GMC Sierra Code - Exhaust Gas Recirculation Flow Insufficient

What does this mean?

What are the Possible Causes of the DTC P0401 2016 GMC Sierra?

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

How to Fix the DTC P0401 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 does this mean?

Code Tech Notes

The EGR flow malfunction could be caused by a clogged EGR valve or EGR tube. Before replacing any parts try cleaning the EGR valve, tube, and passages.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0401 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.

Need more information about the P0401 2016 GMC Sierra code?

Need more information on how to fix the P0401 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0401 2016 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P0401 2016 GMC Sierra Code

What does the OBDII code P0401 mean on a 2016 GMC Sierra?

P0401 indicates "Exhaust Gas Recirculation (EGR) Flow Insufficient," meaning the EGR system isn't allowing enough exhaust gases to re-enter the intake manifold as intended.

What are common symptoms of code P0401 in a 2016 GMC Sierra?

Symptoms may include the Check Engine Light turning on, reduced fuel efficiency, rough idling, engine knocking, or increased emissions.

What causes the P0401 code to appear in a 2016 GMC Sierra?

Common causes include a clogged EGR valve, carbon buildup in EGR passages, a faulty EGR solenoid, a malfunctioning EGR sensor, or vacuum line leaks.

Can I drive my 2016 GMC Sierra with the P0401 code?

While the truck may still be drivable, prolonged operation with this code can lead to reduced performance, higher emissions, and potential engine damage over time.

How can I diagnose the P0401 code on my 2016 GMC Sierra?

Start by inspecting the EGR valve and passages for blockages, check vacuum lines for leaks, and test the EGR solenoid and sensor for proper operation using a diagnostic tool.

How do I fix the P0401 code in a 2016 GMC Sierra?

Repairs may include cleaning the EGR valve and passages, replacing a faulty EGR valve, fixing vacuum line leaks, or replacing the EGR solenoid or sensor if defective.

Is the P0401 code covered under warranty for a 2016 GMC Sierra?

EGR-related components may be covered under the emissions warranty if the vehicle is within the warranty period. Check with your dealership for specifics.

How much does it cost to fix code P0401 on a 2016 GMC Sierra?

Repairs can range from $100 for cleaning the EGR system to $300-$500 for replacing the EGR valve or associated components, depending on labor and parts costs.

Can a dirty air filter cause the P0401 code on a 2016 GMC Sierra?

While uncommon, a severely clogged air filter can restrict airflow and indirectly affect EGR performance, but it's not a primary cause of P0401.

How can I prevent the P0401 code from reoccurring on my 2016 GMC Sierra?

Regular maintenance, including cleaning the EGR valve, using high-quality fuel, and addressing carbon buildup, can help prevent this code from reappearing.