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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35843
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ford F150 Pickup 4x2: I have a 1999 F150 2WD with a 4.6L. I

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I have a 1999 F150 2WD with a 4.6L. I keep getting the ses light and the guy at the auto parts store says the code is low EGR flow. I removed the EGR valve and it appeared to be working fine. When I checked the DPFE sensor, it had condensation in it from the hoses going to the EGR pipe. So I installed a new DPFE sensor and erased the code, it came back on a week later with same code. DPFE sensor full of condensation again. I also already installed a new EGR control solenoid, still get light.
Hello and Welcome to Justanswer, My name is XXXXX XXXXX I am here to try and assist your with your question.

Are you setting the code P0401?
Customer: replied 5 years ago.
The code P0401 does not always mean the DPFE is bad and the fact that you are getting condensation in the DPFE tells me you have a low EGR flow issue and in most cases thats cause by restricted EGR passages.To clean out the EGR passages, remove the throttle body and spacer plate if equipped. Once the inside of the intake manifold is accessible, clean out the passages inside real well and this should resolve your concern. If you need throttle body removal instructions, let me know and I will send right away.

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Customer: replied 5 years ago.

I still have the same problem. The manifold and EGR valve are clean, so its not a blockage issue. I have battery voltage at the EGR control solenoid. I can disconnect the vacuum line going to EGR valve and suck on it and here that the valve is operating smoothly. When I start the truck and leave it in park, the EGR pipe stays cool. Then when I put it in gear, the pipe gets hot like everything is working normal. All the vacuum lines appear to be in good condition also.

So which code are you still setting?
Customer: replied 5 years ago.

Still getting the PO401 code.

If you are sure the passages are clear and the DPFE is connected corrected then you may have a defective DPFE. Run the pinpoint test to recheck.Check the DPFE sensor voltage on the scan tool. A normal Key On Engine Off reading will indicate 0.5-1.2 volts.If the DPFE sensor's voltage is outside the normal range, disconnecting the sensor should result in a reading of 5 volts on the scan tool.If the sensor voltage reacts as stated after disconnecting, , verify 5.0 volts is present at the sensor connection between the Brown/White wire and the Grey/Red wire before replacing the sensor.
Customer: replied 5 years ago.

I dont have my own scan tool, i've been going to the local auto parts store to have them check the code. I did take some voltage readings with a meter and this is what i got at the DPFE connector.

disconnected and engine not running: 5v at brown/white to gray/red.

5v at brown/green to gray/red.


And with plug hooked up and engine running and warmed up:

1v at brown/green to gray/red

4v at brown/white to brown/green

5v at brown/white to gray/red


over the past 4 years, i have put several new DPFE sensors in this truck. It used to keep the ses light off for several months in the begining, but then it started coming back on sooner and sooner. The current DPFE sensor kept the light off for about 1 day, just long enough to get it through inspection. I'm wondering if it has something to do with the CAT converter being restricted or something.

Are you sure the new one insnt defective?
Customer: replied 5 years ago.

The sensor I have now could be bad, but at $60 a pop I always wait til its time to get it inspected before I buy a new one. Every one that I buy works for a little while then when the light comes back on, I remove the sensor and it has water in it. Thats why I'm wondering if the catalytic converter is bad.

Moisture is always a killer on them are you using the new plactic ones?
Customer: replied 5 years ago.

Yep, 100% genuine plastic.

Its not likely the converter plugged up, if so, you would notice a loss in power in most cases.
Customer: replied 5 years ago.

The truck runs pretty good for 192,000 miles, but I have noticed that I cant run 87 octane anymore, or I get pinging under accelleration. 89 or higher and its fine.

With the amount of mile you have on it, you may very well have some exhaust restriction, but it usually dosnt set a DPFE code.
Customer: replied 5 years ago.

I guess I'm just gonna leave it for now. In March when the inspection is due, I'll buy another sensor and hopefully It'll get me through inspection. I just dont know what else to try at this point, that isnt gonna cost a bundle of money.

Okay, let me know if I can help you. Im here every day. I will do what I can.