P0404 — Exhaust Gas Recirculation Circuit Malfunction
Can drive — fix at your convenience.
What P0404 means
This code means the engine computer has detected an electrical problem in the EGR control circuit, so it can't properly command the EGR valve open or closed. It's usually caused by a wiring fault, a bad connector, a failed EGR solenoid, or a faulty EGR valve. Repairs commonly involve fixing the wiring or replacing the solenoid or valve, and it's typically not an expensive job.
Common symptoms
- Check engine light is on
- Rough idle or mild engine shaking
- Light engine knock or pinging under load
- Slight loss of power or hesitation
- Failed emissions or smog test
Common causes
- Faulty EGR valve or solenoid
- Open or shorted EGR control wiring
- Corroded or loose EGR connector
- Failed EGR vacuum control circuit
- Engine computer (PCM) driver fault
Typical repair cost
$150 – $500
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0404 code?
Yes, in most cases you can drive normally since this is an emissions and electrical issue, not a safety hazard. You might notice a rough idle or mild pinging. Get it repaired soon to avoid emissions problems and carbon buildup.
How much does it cost to fix a P0404 code?
Most repairs fall between $150 and $500. A wiring or connector repair is on the cheaper side, while replacing the EGR valve or solenoid with labor pushes toward the higher end.
Is a P0404 code serious?
It's low severity. The car usually runs fine, but the EGR system won't work correctly, which affects emissions and can slowly cause carbon buildup. It's worth addressing but not an emergency.
What does an EGR circuit malfunction mean in P0404?
It means the electrical signal between the computer and the EGR valve isn't working as expected. The valve may not open or close on command, usually due to faulty wiring, a bad solenoid, or a failed valve.