Parts
$0–250
P0401 — EGR Insufficient Flow
SAFEIs it safe to drive? The exhaust-gas-recirculation system isn't flowing enough. Driveable; you may get light knock/pinging and an emissions fail.
What P0401 means
EGR routes a little exhaust back into the intake to cool combustion and cut emissions. This code means not enough is getting through — usually carbon clogging.
Most likely causes (in order)
- Carbon-clogged EGR passages or valve (most common)
- Stuck EGR valve
- Faulty EGR position sensor / DPFE sensor
- Blocked EGR tube
Symptoms you might notice
- Check-engine light
- Light knock/ping under load
- Sometimes rough idle
What to check first
Remove and clean the EGR valve and ports of carbon; check the valve actuates and the position/DPFE sensor reads right.
Repair cost & difficulty
Labor
0.5–2 hr
Difficulty
DIY-friendly
Related codes
P0402P0400