OBD-II code · Powertrain (generic)
P0401 Exhaust Gas Recirculation Flow Insufficient Detected
When the ECU commands EGR open, the actual flow measured by the DPFE sensor or the resulting MAP/MAF change is below threshold. By far the most common cause is a carboned-up EGR valve or blocked intake passages.
Is it safe to drive with P0401?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyEGR valve clogged or stuck closed
- Most likelyIntake EGR passages blocked with carbon
- PossibleVacuum line to EGR (vacuum-actuated valves) cracked
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 1–5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Egr Valve, Egr Passages, Dpfe Sensor
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.