P0401 Code
#5
PCM commands the EGR solenoid to open when @ cruising speeds. Solenoid opens, routing vaccum to pull the egr valve open, so exhaust gases get passed into the intake.
DPFE has two hoses, one is Ref pressure, the other is Signal. When the PCM opens the EGR solenoid and the EGR valve opens, exhaust gas pressure is felt in the Signal hose to the DPFE. This creates pressure against a diaphragm that produces the electrical signal.
http://www.tomco-inc.com/Tech_Tips/ttt33.pdf
Your issue could be a bad hose to the DPFE, bad EGR solenoid (not opening), or carbon is blocking EGR exhaust gas flow.
DPFE has two hoses, one is Ref pressure, the other is Signal. When the PCM opens the EGR solenoid and the EGR valve opens, exhaust gas pressure is felt in the Signal hose to the DPFE. This creates pressure against a diaphragm that produces the electrical signal.
http://www.tomco-inc.com/Tech_Tips/ttt33.pdf
Your issue could be a bad hose to the DPFE, bad EGR solenoid (not opening), or carbon is blocking EGR exhaust gas flow.
#6
I've seen more bad DPFE sensors for that code, and once had to go through about 4 new sensors to find a good one. Even if you just replaced it, it wouldn't hurt to double check it.
"1996 Ford Ranger 2.3L - Confirmed Fix
Vehicle Description: 1996 Ford Ranger 2.3L, Vin A, Eng Cfg L4
Mileage: 161000
Customer Concern: Setting trouble codes P0401 and P1408. The EGR vacuum regulator (EVR) does work when grounded and the Exhaust Gas Recirculation (EGR) valve opens.
Tests: 1. Check the Differential Pressure Feedback EGR (DPFE) sensor voltage Key On Engine Off either on a scanner or by back probing the Brown/Light Green (BR/LG) wire at the DPFE sensor. The voltage should read roughly 0.4-1.1v depending on the sensor.
2. If the voltage is not correct (either above 1.1v or less than 0.4v), verify the Brown/White (BR/WH) wire is a good ground and that the Gray/Red (GY/RD) wire shows a good ground. Also make sure all pin connections are tight. If so, replace the DPFE sensor and retest.
3. If the voltage is correct Key On Engine Off, use a hand vacuum pump and apply 8" Hg vacuum to the "REF" port of the DPFE sensor. The voltage should increase to at least 4v. If it does not, replace the sensor and retest.
Potential Causes: Differential Pressure Feedback EGR (DPFE) sensor
** Confirmed Fix **
Replaced Differential Pressure Feedback EGR (DPFE) Sensor"
Copyright 2009 Identifix, Inc.
"1996 Ford Ranger 2.3L - Confirmed Fix
Vehicle Description: 1996 Ford Ranger 2.3L, Vin A, Eng Cfg L4
Mileage: 161000
Customer Concern: Setting trouble codes P0401 and P1408. The EGR vacuum regulator (EVR) does work when grounded and the Exhaust Gas Recirculation (EGR) valve opens.
Tests: 1. Check the Differential Pressure Feedback EGR (DPFE) sensor voltage Key On Engine Off either on a scanner or by back probing the Brown/Light Green (BR/LG) wire at the DPFE sensor. The voltage should read roughly 0.4-1.1v depending on the sensor.
2. If the voltage is not correct (either above 1.1v or less than 0.4v), verify the Brown/White (BR/WH) wire is a good ground and that the Gray/Red (GY/RD) wire shows a good ground. Also make sure all pin connections are tight. If so, replace the DPFE sensor and retest.
3. If the voltage is correct Key On Engine Off, use a hand vacuum pump and apply 8" Hg vacuum to the "REF" port of the DPFE sensor. The voltage should increase to at least 4v. If it does not, replace the sensor and retest.
Potential Causes: Differential Pressure Feedback EGR (DPFE) sensor
** Confirmed Fix **
Replaced Differential Pressure Feedback EGR (DPFE) Sensor"
Copyright 2009 Identifix, Inc.
#7
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I just went through this with my 4.0. Clean the egr tubes. You will more than likey have carbon build up in the hoses. Disconnect it from the exaust to the intake and clean it really good. And make sure you get the new plastic dpfe sensor not the old metal ones. There is alot of mousture build up in the egr system and if there is alot of carbon buildup in the lines itll clog every time. Also search all the egr lines for small holes. Also I think you will also have a vacum sylinoid that will create the vacum pressure needed to open the egr, but am not sure on the 2.3
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i'm having the same problem with my 1996 with 2.3 also. Now i'm over a month late on getting the emissions test done because it failed saying P0401. I'v replaced EGR vlave, EGR selonoid, egr pressure feedback sensor, both o2 sensors, ect. Can anyone else help me out on what else to replace or check. Thanks
#17
SUGGESTION:::REPLACE THE DPFE WITH A OEM, MOTORCRAFT PART.
These sensor are very delicate, and often times aftermarket parts just dont do it.
Here is a link to a place you can get the OEM part for 46.95
Ford DPFE Sensor
Motorcraft part # DPFE15
Good luck.
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