All Codes/P0401

Code P0401Monitor

EGR Flow Insufficient Detected

Your emissions control system is clogged - like a blocked drain. Engine runs hotter and produces more pollution.

Professional Service
Available
Category
emissions
Common In
Honda Civic

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Monitor and Maintain

This issue is not immediately critical but should be addressed at your next service.

Recommended Actions:

  • Note the code for your next service
  • Monitor for any changes in symptoms
  • Can combine with next scheduled maintenance
  • Check if code returns after clearing

What This Code Means

The exhaust gas recirculation (EGR) system is not flowing enough exhaust back into the engine.

"Your emissions control system is clogged - like a blocked drain. Engine runs hotter and produces more pollution."

Common Causes

1

Clogged EGR passages

2

Failed EGR valve

3

Carbon buildup in intake

4

Faulty EGR position sensor

5

Vacuum line problems

Symptoms You May Notice

Engine knocking or pinging
Rough idle
Failed emissions test
Slightly reduced fuel economy

Professional Diagnostic Steps

Our technicians will perform these checks:

Clean EGR valve and passages
Test EGR valve operation
Check vacuum lines
Inspect for carbon buildup

Commonly Affects These Vehicles

Honda Civic
Toyota Corolla
Mazda6
Ford Fusion
Chevrolet Impala

Note: This code can appear in any vehicle. These are just the most common.

Repair Cost Breakdown

DiagnosisAvailable
Often waived with repair
PartsQuality Options
OEM or quality aftermarket
LaborProfessional Service
Professional installation
Total RangeCall for Quote

Why Choose Us?

  • ASE Certified Technicians
  • Latest Diagnostic Equipment
  • Warranty on All Repairs
  • Upfront, Honest Pricing
  • Same Day Service Available

Frequently Asked Questions About Code P0401

Can I keep driving with code P0401?

Safe to drive but may fail emissions test - repair when convenient

How much will it cost to fix P0401?

The repair approach depends on the specific cause and your vehicle.The most common cause (clogged egr passages) usually costs on the lower end of this range.

Will code P0401 clear itself?

While the check engine light may turn off if the condition improves temporarily, the code will remain stored in your vehicle's computer. The underlying issue still needs to be addressed to prevent the code from returning and potentially causing damage.

Is P0401 covered under warranty?

Many emissions-related repairs are covered under federal emissions warranty (8 years/80,000 miles for catalytic converters and ECM). Check with your dealer.

Don't Guess - Get Professional Diagnosis

Code P0401 can have multiple causes. Our diagnostic process ensures we fix the right problem the first time.