P0401

Just to let every one know I have searched and searched and not come up with a conclusive answer.
99 svt

I have a p0401: low egr flow code. The passages were gunked up cleaned them with no change. the egr solenoid was faulty so I replaced it. The egr valve functions as it should suck on the nipple car sputters and feels like its gonna stall. The only thing i can think of is the dpfe sensor. Is p0401 the code you get from a failing dpfe that the computer still thinks is good?

typically a bad dpfe sensor will show a P0402 code, iirc. however if everything else checks out then it could be the source of the issue.

After reading on some focus and truck forums when the dpfe is reading lower than it should you get the low flow code which the engine try's to compensate for it by giving the egr even more vacuum causing stumble and hesitation at cruising speeds when you lightly give it throttle.

It was the dpfe. I changed it out with a borg warner and voila no more code.

After searching the P0401 code a bit I thought I'd add a bit of info for testing the DPFE Sensor for s&g's. Hopefully it helps someone.

Disconnect the pressure hoses at the DPFE sensor.
Connect a hand vacuum pump to the downstream pickup which should be marked REF on the sensor.
With a multimeter, backprobe the SIG RTN circuit at the DPFE connector.
Ignition ON, signal voltage will be 0.20-0.70 volts.
With the had vacuum pump apply 8-9 in. Hg of vacuum to the sensor. Voltage will be greater than 4 volts.
Quickly release the vacuum from the sensor. Voltage should drop to less than 1 volt in 3 seconds.
If the sensor does not respond as noted check the power and ground circuits.
If power and ground circuits are okay the sensor is faulty.