Hello, new to the site, and new to Ford SuperDuty trucks.

Recently purchased a used 2015 F-350 Lariat Super Crew 4x4 with 40K miles, recent being two weeks ago. This last weekend took it on a shakedown trip, maybe 300 miles round trip and noticed the check engine light was on after passing another vehicle on a two-lane HWY. Gave me a chance for a WOT pass. No drivability issues and the light remained on for the last 70 miles of the trip. The following day at home, cold start still had the light. Connected my code reader with engine off, P0170 came right up. No other faults. Checking while running the diagnostic check came back all OK.

I found some info on the fuel trim malfunction and a TSB, etc. and scheduled a visit to the dealer today to inspect and correct the issue. CEL was on this morning on the way to work, but the start-up for lunch the light was off. I did not reset or clear the code.
I searched this forum for information regarding this code and didn't see anything recent, nor any mention of the CEL going out after this code was set. Has anyone else had this as an intermittent issue? All I've been able to find so far is that the code keeps returning after a manual reset and some possible fixes.

I suspect that the CEL would eventually return, so I'm taking it to the dealer anyway to document the issue in the case it does return. I have a 90 day no deductible warranty, then it's a $300 deductible. So I want as much on file with for the 90 days is up.

Thanks in advance for any input.

Note: While this is my first Ford Super Duty diesel, I've had a 98 and 99 Dodge Cummins, and a 05 and a 06 Chevy D-Max Duallys for fleet vehicles. I loved my D-Max's but coming from a couple of Dodge POS's anything would have been better. Thought I'd try a Ford this time.

 

Your making the right choice to take it to the dealer. It most likely needs the PCM flashed with the newest version, that fixed it for me. My CEL never turned off on it's own, only when I reset it.

https://www.ford-trucks.com/forums/1...l#post17727233

 

The truck was going in any way for the driver's seat heater not working and had them look into the P0170 code. They reported back the seat needs to be ordered, and when I return the PCM will be updated per the TSB also under warranty.

I never mentioned the TSB ahead of time and was refreshing to hear the dealer offer to do it even though the SEL was not illuminated at the time. Apparently the code was still visible in the PCM.

Thanks