P0401 on a Ford: Causes, Fixes & Repair Cost
🟠 Moderate severity · drivable
Safe to drive, but the EGR problem can cause rough idle and an emissions test failure, so schedule the repair soon.
What P0401 means on a Ford
On a Ford, P0401 means the computer detected too little exhaust gas flowing through the EGR system. On Fords, the classic trigger is a failed DPFE sensor — the small sensor that measures EGR flow — which reads low even when the valve itself is working correctly.
Is P0401 common on Fords?
P0401 is one of the best-known codes on older Ford Focus, Taurus, F-150, and Explorer models. The DPFE sensor is the most common failure point on this brand, followed by carbon-clogged EGR passages in the intake manifold.
Commonly reported on: Focus, Taurus, F-150, Explorer.
Symptoms
- Check engine light is on
- Rough idle
- Possible pinging under load
- Failed emissions test for high NOx
Common causes
- most common: Faulty DPFE sensor that reads EGR flow incorrectly
- common: EGR passages in the intake clogged with carbon
- common: EGR valve stuck closed
- less common: Clogged or leaking EGR tube
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Replace the DPFE sensor | Yes | $40–100 |
| Clean the EGR valve and intake passages | Yes | $15–60 |
| Replace the EGR valve | Yes | $100–250 |
Frequently asked questions
Other common Ford codes
P0401 on other brands
Looking for the full (non-brand-specific) guide? See the P0401 code page →
Browse all Ford codes: Ford hub →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.