PO401 EGR flow insufficient code came on. The car shakes when at a stop light and acts like it is going to die. It is slow on acceleration.

po401 is insufficient air flow from EGR valve. check the vacuum hoses from egr, if ok, remove or test the egr valve itself and try to clean it out. Good-Day! It may just be sticking, from carbon buildup.

EGR insufficient flow detected, could be a failing exhaust system creating a blockage,

Code 401 is for low EGR air flow. The EGR valve allows exhaust gas to be recirculated back thru the intake and reburned.
The problem could be the EGR valve, the sensor, or a blocked line.

cleanout egr valve and troutle body . Or replace egr with new one, clean, check vacumm lines , check for clogged check , depending on modle of car you can pippoint problem as some have a common part problem depeding with make of car. But all have to do with exaust system. Insufficient flow exaust flow. Im not an expert, all I know it is related to this, I have it myself so im googling it.

Ford EGR valve

The OBDII fault code P0401 means that the engine computer has detected that the Exhaust Gas Recirculation (EGR) system flow is insufficient. Read more how the EGR system works below. What could cause the code P0401 - clogged or restricted EGR passages
- faulty EGR valve
- EGR valve stuck closed
- problems with the DPFE sensor (Ford)
- problems with hoses to the DPFE sensor (Ford)
- problem with the EGR vacuum switching valve (Toyota)
- clogged catalytic converter
- carboned up EGR temperature sensor
- vacuum supply issues at the vacuum-operated EGR valve
- electrical problems with the EGR valve control circuit
- engine computer problems
helpful website helps you with pinpoint and sou;ution related to auto make and model shows you most common cause of code reading.
www.samarins.com

Code 401 is for EGR flow insufficient.
There is a sensor that measures how much exhaust gas goes thru the EGR valve. The sensor could have failed, or the EGR valve may not be working. The sensor and valve would need to be tested.

PO401: EGR insufficient flow detected
PO402: EGR excessive flow detected

A code P0402 most likely means one or more of the following has happened:

The DPFE (differential pressure) sensor is faulty and needs to be replaced
There is a blockage in the EGR (most likely carbon buildup)
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum

I believe this code is insufficient EGR flow. On this engine, the passages to the EGR valve often become carboned up and cause this code. Remove the EGR valve and inspect the passages to see if they need to be cleaned.

PO-401
EGR Flow Insufficient Detected

PO401 Insufficient EGR Flow, valve could be stuck or disconected.

It could very possibly the EGR tubes are clogged or the EGR is not opening or could be DPFE; first i would check the tubes on the DPFE and also clean the EGR tubes and egr it self simple brake clean and a hanger can clean the tubes and spray some in the EGR it also can get gunked up and not move properly.

Hope this help to solve it (remember comment and rated this).

PO401 code means that:
The PCM has determined that there is insufficient flow in the exhaust gas recirculation system. Definition: EGR system fault (Exhaust Gas Recirculation) Probable Causes: a. Blocked passage on EGR system b. Failed EGR Valve c. EGR solenoid faulty d. Failed EGR pressure sensor where applicable e. Failed EGR position sensor where applicable