Code P0404 (EGR Control Circuit Range/Performance) on the 6.4L Power Stroke means the EGR valve is not responding within its expected range. This guide covers what triggers P0404, how to diagnose it, and the parts that fix it.
What P0404 means
P0404 sets when the EGR valve position does not match the commanded value - a sticking, carboned, or failing EGR valve, or a circuit fault.
Common causes
- Carbon-clogged or sticking EGR valve
- A failing EGR valve motor/position sensor
- Wiring or connector fault
- Restricted EGR passages
Symptoms you'll notice
- Rough idle and hesitation
- Reduced power and economy
- A check-engine light
How to diagnose it
Inspect the EGR valve for carbon and sticking and check that it moves through its range. Verify the wiring and the valve's position feedback before replacing.
The fix
Clean or replace a sticking/carboned EGR valve and clear restricted passages. A quality replacement valve restores proper range and flow.
Frequently asked questions
Can I clean the EGR valve for P0404?
If carbon and sticking are the cause and the valve still moves, cleaning can help. A failed motor or sensor means replacement.
Is P0404 serious?
It hurts drivability and economy and should be addressed, though it is not usually an immediate breakdown risk.
Need the part?
We stock the 6.4L Power Stroke EGR Valve - New Direct-Fit Diesel Replacement for your 6.4L Power Stroke and ship it direct. Shop it →