P0401 on a Nissan: 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 Nissan
On a Nissan, P0401 means the engine computer detected too little exhaust gas flowing through the EGR system. On Nissan 2.5L engines, carbon builds up in the EGR valve and its passages, and the EGR temperature sensor can also read low when flow drops.
Is P0401 common on Nissans?
P0401 shows up on higher-mileage Nissan models like the Altima, Sentra, and Frontier with 2.5L engines. Carbon clogging is the usual cause, and cleaning the EGR system clears many cases without replacing parts.
Commonly reported on: Altima, Sentra, Frontier.
Symptoms
- Check engine light is on
- Rough idle
- Possible hesitation during acceleration
- Failed emissions test for high NOx
Common causes
- most common: EGR passages clogged with carbon
- common: EGR valve stuck closed by carbon
- common: Faulty EGR temperature sensor
- less common: Vacuum leak in the EGR line
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Clean the EGR valve and passages with intake cleaner | Yes | $15–60 |
| Replace the EGR valve | Yes | $100–300 |
| Replace the EGR temperature sensor | Yes | $50–150 |
Frequently asked questions
Other common Nissan codes
P0401 on other brands
Looking for the full (non-brand-specific) guide? See the P0401 code page →
Browse all Nissan codes: Nissan hub →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.