What usually causes it
- Carbon build up that sticks the valve
- A failed EGR valve motor or position sensor
- Damaged wiring or a loose plug
- A vacuum problem on cars with a vacuum valve
P0404Starts at: OK to drive, fix when convenient
EGR valve is not moving the way it should
The EGR system sends a small amount of exhaust back into the engine to keep it cooler and cleaner. The valve is not opening or closing the way the computer asked.
Check this first
Look at the plug and the small rubber hoses on the EGR valve for a loose fit or cracks.
What to watch for
- Rough idle or stalling
- A pinging or knocking noise when you speed up
- Poor gas mileage
Can I keep driving?
We rate P0404 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 P0404
What does P0404 mean?
EGR valve is not moving the way it should. The EGR system sends a small amount of exhaust back into the engine to keep it cooler and cleaner. The valve is not opening or closing the way the computer asked.
Can I keep driving with P0404?
We rate P0404 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 P0404?
The most common causes, in order: Carbon build up that sticks the valve; A failed EGR valve motor or position sensor; Damaged wiring or a loose plug; A vacuum problem on cars with a vacuum valve.
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.