AutoCodes – Chevrolet – P0402 Chevrolet

P0402 Chevrolet 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 Chevrolet 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 4,390

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 Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0402 Chevrolet 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 Chevrolet - Exhaust Gas Recirculation Flow Excessive - AutoCodes.com — P0402 Chevrolet Code - Exhaust Gas Recirculation Flow Excessive

What does this mean?

What are the Possible Causes of the DTC P0402 Chevrolet?

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 Chevrolet?

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 Chevrolet 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 Chevrolet code?

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

Need Help with the Code?

Get the P0402 Chevrolet code diagnosed by a professional: Find a repair shop in your area

Information for Specific Chevrolet Models

P0402 2014 Chevrolet Silverado — Exhaust Gas Recirculation Flow Excessive
P0402 2015 Chevrolet Silverado — Exhaust Gas Recirculation Flow Excessive
P0402 2016 Chevrolet Silverado — Exhaust Gas Recirculation Flow Excessive
P0402 2017 Chevrolet Silverado — Exhaust Gas Recirculation Flow Excessive
P0402 2018 Chevrolet Silverado — Exhaust Gas Recirculation Flow Excessive

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 Chevrolet Code

What does the OBDII code P0402 mean on a Chevrolet?

Code P0402 indicates that the Exhaust Gas Recirculation (EGR) system is allowing too much exhaust flow back into the intake manifold, exceeding the manufacturer's specifications.

What are the common symptoms of code P0402 in a Chevrolet?

Common symptoms include the check engine light turning on, rough idling, reduced engine performance, poor fuel economy, and increased exhaust emissions.

What causes the P0402 code to appear on a Chevrolet?

Common causes include a stuck-open EGR valve, carbon buildup in the EGR passages, a faulty EGR sensor, or issues with the engine control module (ECM).

Can a faulty EGR valve trigger the P0402 code?

Yes, a stuck-open or malfunctioning EGR valve is one of the primary causes of the P0402 code.

How can I fix the P0402 code on my Chevrolet?

Repairs may involve cleaning or replacing the EGR valve, clearing carbon buildup in the EGR passages, replacing a faulty EGR sensor, or addressing wiring issues.

Is it safe to drive my Chevrolet with the P0402 code?

Driving with the P0402 code is not recommended, as it can lead to poor performance, higher emissions, and potential engine damage if left unaddressed.

How much does it cost to fix the P0402 code on a Chevrolet?

Repair costs vary, but replacing an EGR valve typically costs between $150 and $400, including parts and labor. Cleaning the EGR system is less expensive.

Can a vacuum leak cause the P0402 code?

A vacuum leak is not a direct cause of P0402, but it can contribute to irregular EGR system operation, which may trigger the code.

How do I diagnose the P0402 code on my Chevrolet?

Diagnosis involves scanning for trouble codes, inspecting the EGR valve for sticking or damage, checking for carbon buildup, and testing the EGR sensor and related wiring.

Can a clogged catalytic converter cause the P0402 code?

While uncommon, a clogged catalytic converter can sometimes cause backpressure issues that may affect EGR system performance, potentially triggering the P0402 code.