P0401
Medium SeverityEGR Insufficient Flow
Emissions System
What Does P0401 Mean?
The EGR is not flowing enough exhaust gas. Usually carbon buildup blocking the passages.
Common Fix
Clean EGR valve and passages
Estimated Cost (DIY)
$20 - $150
Symptoms
- ⚠️Ping/knock under load
- ⚠️Failed emissions test
- ⚠️Check engine light
Related Symptoms
Common Causes
How to Diagnose P0401
- 1Clean EGR valve and intake passages
- 2Test EGR valve with vacuum pump
- 3Check DPFE/EGR pressure sensor
OEM Diagnostic Flowchart
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0401.
OEM Manual Evidence
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Related Symptoms
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Open the exact vehicle hub for a repair workflow commonly associated with P0401.
Open the exact vehicle hub for a repair workflow commonly associated with P0401.
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Open the exact repair flow most commonly associated with P0401 on this vehicle.
Open the exact repair flow most commonly associated with P0401 on this vehicle.
Open the exact repair flow most commonly associated with P0401 on this vehicle.
Open the exact repair flow most commonly associated with P0401 on this vehicle.
Related Codes
Frequently Asked Questions
- Can I clean the EGR valve myself?
- Yes — remove it and clean with carb cleaner and a brush. Also clean the intake port/passage.
- Is P0401 common on certain cars?
- Very common on Fords with the DPFE sensor. Replacing the DPFE sensor often fixes it for $30-$50.
Related Repair Guides
If your vehicle has triggered P0401, these DIY repair guides may help: