Exhaust Gas Recirculation Flow Insufficient Detected

What is P0401?

P0401 indicates your vehicle's computer has detected insufficient exhaust gas recirculation (EGR) flow, which is part of the emissions control system. This is a medium-severity issue that can cause failed emissions tests and reduced fuel efficiency. Based on real owner data, this code appears most frequently in Honda Accord and Ford Mustang models.

Common Causes

• ●Clogged or stuck EGR valve passages (most common issue reported)
• ●Faulty EGR valve itself
• ●Blocked EGR cooler or lines
• ●Malfunctioning EGR position sensor or DPFE sensor

Symptoms You May Notice

• ●Check Engine Light illuminated (universal symptom)
• ●Reduced engine performance or hesitation during acceleration
• ●Increased fuel consumption
• ●Rough idle or engine stalling
• ●Failed emissions inspection

How to Fix It

• ●Clean or replace EGR valve and passages ($150-$400, moderate difficulty)
• ●Replace entire EGR valve assembly ($300-$600, moderate difficulty)
• ●Clean or replace EGR cooler and lines ($200-$500, moderate difficulty)
• ●Replace EGR position sensor or DPFE sensor ($100-$250, easy to moderate difficulty)