egr passage way in engine plugged with carbon. will off of engine, make sure egr is ok.
I had the same thing happen to my car that code means insufficent egr flow. You have to replace the egr valve.
EGR insufficient flow would mean that either the flapper inside of the valve is either stuck or broken, or the rubber diaphragm is busted inside, You would have to replace the EGR valve its self. = =
The code depends on the manufacturer. Get it to autozone and have it tested, they will give you a printout of the most probable causes. What kind of car and engine is it? For a ford, p0401 insufficient flow within the egr system. it is most likely then a dpfe sensor or a clogged passage in the egr system. cheap fix.
DPFE sensor
the egr flow sensor is internal to the egr valve very common problem egr valve needs to be replaced
This is only an emmisions issue and means only that a sensor has determined that the amount of Exhaust Gas Recirculation that is being introduced into your intake manifold via the EGR valveisn't quite enough. The vacuum or electrical valve that opens the EGR valve itself isn't quite working properly. Your vehicle should probably still be running OK ; check the EGR solenoid or vacuum connection for defects if possible.
The egr position sensor is part of the valve. It does not have a flow sensor.
if the code that's comming up is insufficent flow make sure that the opening in the intake where the egr sets ove is not blocked by carbon build up try sticking a piece of wire though the opening if it goes in and doesnt bind up its not clogged (opening goes from egr to tbody opening
The generic OBDII descriptions are EGR Flow insufficient and EGR Flow Excessive.
Plugged EGR passage which restricts the flow of exhaust gasses, faulty EGR solenoid, faulty EGR solenoid wiring/harness, vacuum lines damaged or disconnected to the EGR valve solenoid or to the EGR valve, or a faulty EGR valve.
P0401 - EGR flow insufficient , P0402 EGR flow excessive