P0401 Exhaust gas recirculation flow insufficient
- System
- Powertrain - engine and transmission
What P0401 means
"Exhaust gas recirculation flow insufficient" is a comparison between what was asked for and what was measured. The computer commands a share of exhaust gas back into the intake and then checks how much actually moved; this code is filed when the measured flow came in below what was commanded. P0402 is the same comparison the other way.
This is a standard code. It means the same thing on every make of vehicle.
What the program shows for P0401
Commanded EGR and EGR error are both on the Dashboard, and the second is exactly the difference this code is about: what was asked for against what the car reports it got. The Full scan's on-board self-tests give the EGR and VVT result by bank, and the Inspection screen reports the exhaust gas recirculation monitor.
The Dashboard shows Commanded EGR, EGR error, Evap purge, Catalyst temp, O2 sensor (rear), Fuel level and Coolant temp. The Full scan's On-board self-tests list the Catalyst bank, EGR / VVT bank, EVAP leak, EVAP purge flow, EVAP purge valve and Secondary air results as PASS, FAIL or NO RESULT against the car's own limits, and the Inspection screen shows whether the Catalytic converter, Fuel vapour system, Exhaust gas recirculation and Secondary air injection monitors are done or still running. Clear codes warns that clearing resets those monitors.
See how the program shows a code →