Originally Posted by Butch Golding
I got p0401 insuffeciant flow new egr and cleaned fuel system still same code
Here are 4 other reported fixes:
Replaced Differential Pressure Feedback EGR (DPHE) Sensor
Cleaned EGR Passages
Cleaned EGR Transfer Tube
Replaced EGR Modulator
DPFE Sensor Downstream Hose Off or Plugged
DPFE Sensor Hoses (Both) Off, Loose, or Damaged
DPFE Sensor Hoses are Reversed (Installed Wrong)
DPFE Sensor Reference Circuit (5volt) is open or shorted to ground
DPRE Sensor Signal Circuit is shorted to ground
EGR Orifice Tube is damaged or restricted
PCM has failed
The printout for the p0401 code repeated each of these causes twice for each suggestion, so more than one item may be present and both should be checked [or replaced] in that case.
These are merely suggested causes and fixes, and carries with them NO Liability for this advice.