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I started getting the 401 code... cleaned my throttle body, sea foamed the truck, replaced the egr valve, and now I’m getting 0405, I’ve read about replacing the dpfe sensor but isn’t it built into the egr valve? I don’t know what else to do to this truck. It’s a 4.6 2008 stx with 160k miles.
Just lifted this to see if it can help you Maybe clean connectors with contact cleaner . Hopefully a 4.6 guy will help you out more .
Possible Solutions If you have access to a scan tool you can command the EGR valve on. If it responds and the feedback indicates the valve is moving properly then the problem may be intermittent. Sometimes in cold weather, moisture can freeze in the valve causing it to stick. After the vehicle warms up the problem may disappear. Carbon or other debris can lodge in a valve causing it to stick also If the EGR valve doesn't respond to your commands with the scan tool, disconnect the EGR harness connector. Turn the key to on position, engine off (KOEO). Using a voltmeter, check for 5 volts on the reference wire to the EGR valve. If there is no 5 volts, is there any voltage at all? If there is 12 volts, then repair short to voltage in the 5 volt reference circuit. If there is no voltage connect a test light to battery voltage and probe the 5 volt reference wire. If the test light illuminates, the 5 volt reference circuit is shorted to ground. Repair as necessary. If the test light doesn't illuminate check for an open in the 5 volt reference circuit. Repair as necessary If there is no apparent problem and there is no 5 volt reference, PCM may be at fault, however other codes will likely be present. If 5 volts are present on the reference circuit, jumper the 5 volts to the EGR signal circuit. Now the EGR position on the scan tool should read 100 percent. If it doesn't connect test light to battery voltage and probe the EGR signal circuit. If it illuminates, then the signal circuit is shorted to ground. Repair as necessary. If the light doesn't illuminate, check for an open on the EGR signal circuit. Repair as necessary. If, after jumpering the 5 volt reference circuit to the EGR signal circuit the scan tool EGR position reads 100 percent, then check for poor terminal tension at the EGR valve connector. If the wiring is okay, replace the EGR valve. Related EGR codes: P0400, P0401, P0402, P0403, P0404, P0406, P0407, P0408, P0409
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
picture of dpfe ?
- electrical problems with the EGR valve control circuit
- engine computer problems
Pulled this from another forum... Then alas, while reading on this site, someone mentioned a couple holes about the size of a pencil. I had not seen any such holes anywhere. Then I read about cleaning the trottle body. So I pulled the trottle body off and WOW!!! There were 2 piles of "tobbaco clumps" packed in on top of those 2 ports. After cleaning those 2 holes out, turned out they are a little bigger that 3/8 inch holes. Could have fooled me, they were packed solid.
Cleaned it all up and put it back together. Problem solved.
Just as an update if anyone is having issues with this, I replaced mine with an aftermarket brand EGR Valve...and exchanged it twice, then I resoldered some wires, same issue with a new code. Just to check that I wasn't crazy I went to the junk yard, got a motorcraft EGR valve for 5 bucks, and everything fixed itself. Long story short, just buy OEM parts.
Pulled this from another forum... Then alas, while reading on this site, someone mentioned a couple holes about the size of a pencil. I had not seen any such holes anywhere. Then I read about cleaning the trottle body. So I pulled the trottle body off and WOW!!! There were 2 piles of "tobbaco clumps" packed in on top of those 2 ports. After cleaning those 2 holes out, turned out they are a little bigger that 3/8 inch holes. Could have fooled me, they were packed solid.
Cleaned it all up and put it back together. Problem solved.
I realize this is 6 years old now, but what holes are being referenced here?
Low flow on a 4.6 is generally clogged EGR ports
Low flow on a 5.4 is generally a bad DPFE sensor or no vacuum signal to the EGR valve
You should perform the pinpoint tests to verify the problem and solution before buying any parts
P0405 Code...
