P0401Moderate
Code P0401 — Exhaust Gas Recirculation Flow Insufficient
The P0401 code indicates that the Exhaust Gas Recirculation (EGR) system is not flowing enough exhaust gas back into the intake manifold. The EGR system reduces NOx emissions by recirculating a portion of exhaust gas. When the ECM commands EGR flow and detects insufficient flow via the MAP sensor or EGR position sensor, P0401 is set.
Common Causes
- ▸Clogged EGR valve
- ▸Faulty EGR valve solenoid
- ▸Blocked EGR passages
- ▸Faulty differential pressure sensor
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🏛️ Official Safety Data
From NHTSA — U.S. National Highway Traffic Safety Administration
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