Check engine light flashes for 20-30 seconds on startup
10-08-2026, (Subject: Check engine light flashes for 20-30 seconds on startup ) 
Post: #1
Check engine light flashes for 20-30 seconds on startup
I have a 2014 T6 80 with an ISX 15 that has been put on a diet by a member of this forum. it has given me absolutely zero issues but starting this week, the check engine light with a wrench in the middle of it flashes for about 20 to 30 seconds every time I start the truck. It has never done this before I had the oil changed on it a month ago along with fuel filters and I do not recall the issue starting immediately after that this is a farm truck that does not see a lot of miles that sees a lot of hours and it is harvest season coolant level is fine. The truck does not get over 180 or 185 degrees. Thoughts?
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10-08-2026, (Subject: Check engine light flashes for 20-30 seconds on startup ) 
Post: #2
RE: Check engine light flashes for 20-30 seconds on startup
Kind of sounds like it might be telling you the fuel water sep is full? My pete flashes similar if the sep has water in it.
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10-08-2026, (Subject: Check engine light flashes for 20-30 seconds on startup ) 
Post: #3
RE: Check engine light flashes for 20-30 seconds on startup
Plug into it and see what it wants, we could sit around and guess like idiots for a year.
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 Thanks given by: hookliftpete
10-08-2026, (Subject: Check engine light flashes for 20-30 seconds on startup ) 
Post: #4
RE: Check engine light flashes for 20-30 seconds on startup
Thanks! The sensor was not plugged in. Cleaned it and connected it and everything works.
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 Thanks given by: Rawze




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