P0401
Exhaust Gas Recirculation Flow Insufficient Detected
Description
Exhaust Gas Recirculation Flow Insufficient Detected. This powertrain diagnostic trouble code covers the engine, the fuel and ignition systems, emission control and the transmission.
OBD Codes Details
Possible Causes
Failed catalytic converter, leaking EVAP hoses or purge valve, clogged EGR passages, faulty oxygen sensor
Solution
Check upstream and downstream oxygen sensor readings, smoke-test the EVAP system, inspect the EGR passages and valve, evaluate catalyst efficiency
Symptoms
- Check engine light illuminated
- Engine pinging or knocking, especially under load
- Rough idle
- Increased NOx emissions, failed emissions test
- Hesitation during acceleration
Diagnostic Recommendations
- Inspect EGR valve for carbon buildup preventing it from opening
- Test EGR valve operation with a scan tool
- Check EGR passages and ports for blockage
- Inspect EGR solenoid and vacuum lines (if equipped)
- Verify EGR flow using live data during a commanded test
Repair Cost Estimate
- EGR valve cleaning: $50-150
- EGR valve replacement: $150-450
- EGR passage cleaning: $100-300
- Diagnostic scan: $80-150
- Total diagnostic and repair: $150-800
Was this helpful?
Loading...
Send Feedback
Found an error or have a suggestion? We respond within 48 hours.
Fact-checking completed
Verified by:
Pavel Volkov
Created:
Information verified against official sources
Official Sources
Society of Automotive Engineers
Official OBD-II diagnostic trouble codes standard (SAE J2012)
Automotive engineering standards organization
International Organization for Standardization
International standard for vehicle diagnostic systems
International standards for automotive diagnostics
Learn More
Dive deeper with our comprehensive developer guides for OBD Codes
Related Codes
More codes of the same type