PO401 resurfaced on road trip. I'll try the temp sensor next.
P0401 Defeated - with pics (2 Viewers)
- Thread starter Flank
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PO401 resurfaced on road trip. I'll try the temp sensor next.
I did exactly like the OP did and found te initial clog at the throttle body intake and then checked the passage on the intake by the egr, which was clear.
I then replaced all the hoses I could reach with new ones, and cleaned the filter in the modulator.
I also found a clogged passage on the driver side of the manifold where I used a 1/16" drill bit to get the hardened soot out. See pic
My CEL popped after 30 miles but when I got it checked at advancedauto I got a different code for a heat sensor... P0125?
So hopefully I can research this issue, but happy the 401 code cleared!
--update: I think it could be the ect sensor or temp switch sender. But I need to run the suv to cycle thru and see if it produces the same code.
I then replaced all the hoses I could reach with new ones, and cleaned the filter in the modulator.
I also found a clogged passage on the driver side of the manifold where I used a 1/16" drill bit to get the hardened soot out. See pic
My CEL popped after 30 miles but when I got it checked at advancedauto I got a different code for a heat sensor... P0125?
So hopefully I can research this issue, but happy the 401 code cleared!
--update: I think it could be the ect sensor or temp switch sender. But I need to run the suv to cycle thru and see if it produces the same code.
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Great job wish I could have the chance to give you a hand and get some experience in and see your tire carrier in person. My 96 has the same problem and need to tackle it soon. In case I missed it How did you spend in parts and did you order locally or from CDan.
Flank
American by Birth, Texan by the grace of God.
- Thread starter
- #65
According to my FSM, there is no such code as a P01025, but there is a P0125 - Insufficient Coolant Temp for Closed Loop Fuel control.
-After the engine is warmed up, heated oxygen sensor output does not indicate RICH even once when conditions A,B,or C continue for at least 1.5 minutes:
a) engine speed: 1500 rpm or more
b) vehicle speed 25-62 mph
c) Closed Throttle Position Switch: Off
According to the FSM, this may be due to:
-Open or short in heated oxygen sensor unit
-Heated oxygen sensor
I hope this helps.
Thanks flank! But I think this p0125 code may be fluke since it is the first time my 80 encountered this. Also, I had the obdii on while the engine was not running and the ignition to only on--so that could explain the sensor reading cold? Or am I way off here?
Since I had reset the codes, it's been only 20 miles and haven't fully cycled yet so I'm hoping the cel stays dormant
Update:
Well the cel came on at 37 miles! I'll get it scanned tomorrow. Bummer.....
Since I had reset the codes, it's been only 20 miles and haven't fully cycled yet so I'm hoping the cel stays dormant
Update:
Well the cel came on at 37 miles! I'll get it scanned tomorrow. Bummer.....
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I have been dealing with the P0401 since I purchased my truck last year. Finally decided I had enough and started to tackle the job using this thread as a good source of info. First step was replacing many vacuum lines that had turned to plastic. Then I found the vacuum modulator would not hold vacuum on the bottom port so I replaced it but still go the P0401, however the engine was much happier without that vacuum leak. So today I decided to dive in and checked the egr valve, function seemed ok so I pulled the throttle body to find the EGR port totally plugged. It was quite difficult to chisel out all of the carbon. I also found I had little to no vacuum out of the small vacuum ports on the throttle body, they were all plugged with carbon too. I took some time to replace more vacuum lines under the manifold and clean the throttle body. Drove home tonight and the P0401 did not come back which it normally would have.
Yeah. I found that out the hard way too. I replaced my idle position sensor. When I re-started the truck I thought I had installed the sensor incorrectly because the engine was roaring. Upon further debugging I found that the computer has to reset after you reconnect the idle position sensor. You simply have to shut down the truck after it has warmed up and then restart it and you are good to go.
mechanic. Started right up, CEL is still gone.
im always shocked how much goop is collected in a mere few weeks from the pcv to intake. I threw on a filter/collector on that line and theres a good tablespoon of sludge that are filter out prior to getting into the intake.
imho- this is 90% of that black sludge that gets caked on the intake.
imho- this is 90% of that black sludge that gets caked on the intake.
I have tried to clean the passage hole on the upper intake with a finishing nail as some other posts have recommended, but only made it worse. Now the metal tube is pushed in....flushed with the manifold.
My question is that if I remove the upper intake manifold, can I have access to pulling that metal pipe back out?
My question is that if I remove the upper intake manifold, can I have access to pulling that metal pipe back out?
...just run a new piece of hose from the EGR straight to the EGR VSV and bypass the passage hole through the upper manifold at least until you have figured out how to unclog the passage. I just did this and will probably never bother to unclog the passage hole. I used constant tension clamps on both ends of the new hose as well.
Excellent write-up!
Do you guys know if the passage hole pipe running from top to the bottom of the intake manifold if it is one piece or two separate pieces? If it's one long pipe, can't I access from the bottom of the manifold and push it back up? Why such a design? My guess is temp related?
No idea if it's 2 pieces or 1. I simply bypassed it and probably won't ever think about the passage hole through the upper manifold again.
Subscribed.
Flank you are my hero! Love your quotes and your advise on how to get rid of that fricken P0401 Code! This is no doubt my problem too. . . I think the tell-tail here is that fricken pinging at the point where you are just giving it enough gas to keep at speed. That has driven me nut for way to long. . . ! Thanks for the colorful blow by blow on your aggravation. Someone had to share and I'm thankful you did. Cruise on Brother. . . !
Flank- thanks a ton for all the documentation. Guys like you make Mud a fantastic resource. I just need two more feet of ratchet extensions (on order
) and I can finish up my EGR system overhaul. I was about to document my own adventure into this before I found your write up. I'll report back if there are any significant differences for my '94.
) and I can finish up my EGR system overhaul. I was about to document my own adventure into this before I found your write up. I'll report back if there are any significant differences for my '94.
call me dumb but can some one who has done this post pictures and step by step? or email?
thanks mat
thanks mat
