Diagnostic Trouble Code
P0401 — EGR Flow Insufficient
EGR Flow Insufficient
Definition
The EGR (Exhaust Gas Recirculation) system is not flowing enough exhaust gas back into the intake. The EGR system reduces combustion temperatures to lower NOx emissions.
Common Causes
- Carbon buildup blocking EGR passages
- Faulty EGR valve (stuck closed)
- Clogged EGR tube or intake ports
- Failed EGR position sensor or DPFE sensor