What P0401 means
The exhaust gas recirculation system is not flowing the amount of exhaust the ECU expects.
Common causes
- Carbon-blocked EGR passages
- Stuck EGR valve
- Failed DPFE or EGR position sensor
- Blocked EGR cooler
How it is usually fixed
- 1Remove and clean the EGR valve and passages
- 2Test the position sensor
- 3Replace the valve if it will not seat
Other common codes
- P0011 — Camshaft Position A – Timing Over-Advanced (Bank 1)
- P0030 — HO2S Heater Control Circuit (Bank 1, Sensor 1)
- P0101 — Mass Air Flow Circuit Range/Performance
- P0113 — Intake Air Temperature Sensor Circuit High
- P0118 — Engine Coolant Temperature Sensor Circuit High
- P0131 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
Code information is general guidance, not a diagnosis for a specific vehicle. Confirm with live data and manufacturer test procedures before replacing parts.