Code P1401 and operational temp not reached


ben_2_go

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2001 2.5L automatic. I recently purchased a data logging scan tool and took my truck for a 20-minute joy ride. It's been running rough and getting about 175 miles from a tank of fuel. When I got back from the trip, I got the dreaded P1401 code and another response," vehicle operational temperature not reached". I checked over the EGR system. Everything looks fine. All the hoses are there and the EGR valve is holding vacuum. The sensor may be faulty. I'm not sure if that can be checked or just toss a new one on. What do you use to clean the EGR valve? The engine temp recorded by the scan tool shows a high temp of 190.0 with an average temp of 174.5. A few years ago, I replaced the timing belt and while I was there, I replaced the water pump and T-stat, a 195F unit. The system is full as well as the overflow tank having a little coolant in it. I also have excellent heat. Could the problem be a faulty engine temp sensor?
 


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rgurleyjr

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2001 2.5L automatic. I recently purchased a data logging scan tool and took my truck for a 20-minute joy ride. It's been running rough and getting about 175 miles from a tank of fuel. When I got back from the trip, I got the dreaded P1401 code and another response," vehicle operational temperature not reached". I checked over the EGR system. Everything looks fine. All the hoses are there and the EGR valve is holding vacuum. The sensor may be faulty. I'm not sure if that can be checked or just toss a new one on. What do you use to clean the EGR valve? The engine temp recorded by the scan tool shows a high temp of 190.0 with an average temp of 174.5. A few years ago, I replaced the timing belt and while I was there, I replaced the water pump and T-stat, a 195F unit. The system is full as well as the overflow tank having a little coolant in it. I also have excellent heat. Could the problem be a faulty engine temp sensor?
Not sure the egr has anything to do with the coolant temp, I wouldn't spend any time on that. The temp sensor can be checked, google and see. Sounds like your T-stat may be stuck open...
 

ben_2_go

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Not sure the egr has anything to do with the coolant temp, I wouldn't spend any time on that. The temp sensor can be checked, google and see. Sounds like your T-stat may be stuck open...
It's in the emission system along with a faulty thermostat. The truck runs like it has a vacuum leak. We have been having steady rains since I figured out the problem. I haven't had a chance to do the diagnostics on the EGR control sensor. I can't even remember what that little gray box is named now. Oh yeah, DPFE sensor. I wish I had my garage back.
 

Dirtman

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2001-2002 Rangers have a TSB about code P1401 caused by poorly designed DPFE sensors. All new DPFE sensors have been upgraded to address the issue.

Symptoms of the issue are poor fuel economy, low power, rough idle etc.

Replace the DPFE with the updated version....
 
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ben_2_go

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2001-2002 Rangers have a TSB about code P1401 caused by poorly designed DPFE sensors. All new DPFE sensors have been upgraded to address the issue.

Symptoms of the issue are poor fuel economy, low power, rough idle etc.

Replace the DPFE with the updated version....

Thanks. I knew about that. The one that's on the truck now is a replacement not the OE. It was replaced before my GF bought the truck in 2003 with 50,000 miles on it. I had planned to replace the DPFE when I replace the thermostat.
 

Dirtman

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K.. Try yelling at it
 

ben_2_go

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K.. Try yelling at it
Everyday. :icon_rofl:


I have a new one on order. It is the problem. I am surprised the OE replacement went bad. They usually last longer than the vehicles they go in.:icon_confused:
 

ben_2_go

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Replaced the DPFE sensor today and reset the codes. I drove the truck about 50 miles today. It's better but nowhere close to running properly. I am still getting the P1401 code and a high idle around 900 to 1000 rpm. I'm also getting codes P0133 (O2 circuit slow response) and P0141(O2 heater circuit malfunction). My GF said her brother run the throttle stop screw in because the truck kept stalling on her. How do I reset the throttle stop screw? I think I need to do this before I move onto the other issues.
 


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