P0401 & P0402 codes | Ford Explorer Forums - Serious Explorations

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P0401 & P0402 codes


New Member
December 4, 2006
Reaction score
City, State
St. Louis, MO
Year, Model & Trim Level
2000 XLT
I have been trying to resolve P0401 & P0402 codes. To date, I have replaced the DPFE and the EGR valve.

I replaced the DPFE first about 3 months ago after I saw it had melted on the back left side, including the top part of the tube. I got the P0402 code a short time afterward. I talked the Autozone clerk into replacing the DPFE for free. Now a few months down the road, I’m getting a P0401 code. I replaced the EGR valve and cleared the codes. I got the P0401 again the next day. Any ideas what I should do next?

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I just replaced my dpfe sensor, and it took care of a p401. you replaced egr and dpfe??...hmm...I'd check the hoses, especially dpfe, make sure they have good connections and that the dpfe hoses don't have water in them. Next, i'd check egr solenoid, and engine temp control sensor. These are all interconnected to the ecm.

I double checked:thumbsup: all connections and they looked good. I just replaced the egr solenoid and the no CEL came on today. I will keep my fingers crossed that it was the culprit. Thank you.

I had both of these codes on my '96 Explorer. I got the needed sensors replaced, but still that pesky 'Check Engine' light wouldn't go away and I couldn't get a passing Texas inspection sticker, because the sensors were not in 'Ready' state. Even after driving 300-350 miles, although the mechanic and inspection tech said 40-100 miles are typically enough to put the sensors into 'Ready' state.

Finally, I turned off my car, I restarted it, and let the car idle for over 5 minutes. Within 20-25 miles, the 'Check Engine' went away and the sensors went back into 'Ready', and the car passed inspection.

The CEL came back on. I read the other links and one variable that I have is that I drive about 10 miles to work a day. It mentioned that short trips don't allow for water to dissipate and can damage the DPFE. I have actually replaced the DPFE twice within 3 months. I will try letting the vehicle idle for a while and take it for a longer drive and see if I can put the sensor in a ready state. :(