What usually causes it
- Clogged EGR passages from carbon build up
- An EGR valve stuck closed
- A faulty EGR sensor or a cracked vacuum hose
- A bad control solenoid
P0401Starts at: OK to drive, fix when convenient
EGR flow is too low
The EGR system sends a small amount of exhaust back into the engine to keep it cooler and cleaner. Less exhaust is flowing than the computer expects.
Check this first
Look at the small rubber hoses on the EGR valve for cracks or loose ends.
What to watch for
- A pinging or knocking noise when you speed up
- Rough idle
- Poor gas mileage
Can I keep driving?
We rate P0401 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
Quick answers about P0401
What does P0401 mean?
EGR flow is too low. The EGR system sends a small amount of exhaust back into the engine to keep it cooler and cleaner. Less exhaust is flowing than the computer expects.
Can I keep driving with P0401?
We rate P0401 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
What usually causes P0401?
The most common causes, in order: Clogged EGR passages from carbon build up; An EGR valve stuck closed; A faulty EGR sensor or a cracked vacuum hose; A bad control solenoid.
Estimates only. A mechanic should confirm. The same code can mean slightly different things on different cars; the app explains it for your exact year, make, model and mileage.