What to do about a P0404 fault code
An EGR valve that won't follow orders can leave the engine stalling or short of power, and carbon only makes it worse. P0404 means the valve's position doesn't match what the engine computer asked for, and we can test it where the vehicle is parked.
Can you keep using it with P0404?
Fine for now
If the engine idles smoothly and pulls as normal, everyday use for a short while is usually fine. The valve is probably sticking only now and then.
Get it booked this week
A hunting idle, hesitation when pulling away or the light coming back after clearing mean the valve is getting worse. Book a check before it sticks for good.
Stop and call us
Stop if the engine stalls repeatedly when you slow down or goes into limp mode. An engine that cuts out in traffic is dangerous, and a valve stuck open will keep doing it.
Signs that go with P0404
- An idle that rises and falls on its own
- Stalling as you come to a stop
- A stutter from low revs as you set off
- Black smoke under acceleration
What P0404 means
The official definition is EGR control circuit range/performance. The ECU commands the EGR valve to a position and reads back where it actually went. P0404 sets when the two figures don't agree, meaning the valve is slow, sticking or reporting the wrong position.
Common causes
Carbon on the valve
Soot and oil vapour bake onto the valve and its seat, so it drags or stops short of where it's sent.
A worn valve motor or position sensor
The motor may not have the strength to move a dirty valve, or its built-in sensor may report the wrong position.
Wiring and connector faults
A poor connection can make the valve respond late or the position signal flicker, which looks like a sticking valve to the ECU.
What to do right now
- Pull over safely if the engine stalls or loses power, then restart.
- Note when it happens, whether it's from cold, at idle or under load.
- Keep the revs a little higher when slowing down if stalling is a problem, until it's checked.
- Avoid clearing the code repeatedly. It comes back and the useful freeze-frame data goes.
- Book a check with the registration and any other codes showing.
How we sort P0404 where the vehicle is parked
We read the codes, then command the valve open and closed while watching its reported position on live data. That tells us whether it's carbon, the motor, the sensor or the wiring, for £100 + VAT. If the valve needs replacing, a garage can fit it, and our EGR valve replacement cost guide covers the likely spend.
An EGR delete is £220 + VAT. Many 2018-on Rangers showing P0404 have the locked SID212 ECU, which is unlocked off site in 7 days for £1,200 + VAT. If the vehicle can't be moved, say so when you book.
Reviews
Will P0404 put the car into limp mode?
Some vehicles do cut power with P0404, especially if the valve sticks open. Others just light the warning and carry on.
How long can I leave P0404 before it gets worse?
Carbon keeps building, so a valve that sticks occasionally tends to stick more often. A few weeks is often enough for it to become constant.
Can P0404 damage the engine?
Not directly, though a valve stuck open sends extra soot into the intake and DPF. That can lead to a blocked filter and more cost later.
Will my car pass its MOT with P0404 showing?
No. With the engine management light lit, it fails the MOT before emissions are even tested.
Is P0404 something I can fix myself?
Can an EGR delete stop P0404 on a road vehicle?
No. We only carry out EGR deletes for off-road and export use, and Is EGR delete legal? explains why.
Get P0404 looked at where the vehicle is parked
Tell us where the car or van is and when it stalls or stutters, and we'll come out and test the valve.
More fault codes explained
Eccles, Manchester M30 0SF