a little help

[bigblock_doc]

Got codes p2059, p203f, p0871, Truck had recall valve body done 80,000 ago. The bell went off and the trans went from 1st to 4th and would not shift down or up. Lucky I was a mile from the house. Started off in 1st and by 17mph into 4th it went. Earlier in the day a message came up in the info area, it said would shut down engine or derate after 150 miles. Well put 250 on it and then the bell and trans acted up. Where do I start?
Three codes, one def which could make the trans shift crazy, like limp mode. Or one says I need a new pressure switch, or valve body again. or one that says I need a new computer. Any help, please.
Thanks beforehand.
2019 3500 dually
68rfe
172,000 80,000 on valve body
Truck has been great until now, no problems.

 

[sag2]

P2059 code does not come up. P203F means the fluid is low or there is a problem with the level sensor. P0871 is the one that is causing the transmission to go into limp mode. DEF codes will not cause the transmission to go into limp mode.

 

[Ozymandias]

Always check the filter(s) in the transmission first.
The Primary tends to split if aftermarket and the Secondary can fall off if over torqued.

 

[bigblock_doc]

Sorry, its p2509

 

[sag2]

P2509 has been around for years. It does not mean you need a new ECM. It means the ECM lost power while the ignition was on. Check all battery cable connections and remove and reseat the ECM connectors checking for corrosion. Also a bad battery or crossover cable can cause it.

 

[bigblock_doc]

Cleaned all cables, want a pain. To truck for a 60 mile drive, highway and city.
Checked codes again and none showed up. No codes found. Now, do I trust it to
go on a trip???

 

[NIsaacs]

Has the transmission been serviced since the valve body @ 80k?

 

[bigblock_doc]

Going out right now to do it with Mopar filters.

 

[NIsaacs]

Going out right now to do it with Mopar filters.

Just an FYI if you don't have the fluid yet, Napa has a big sale on Valvoline ATF+4.

https://www.turbodieselregister.com/threads/valvoline-atf-4-on-sale-at-napa-this-month.272838/

 

[bigblock_doc]

Well, did the trans fluid and filters, drove it for 20 miles, checked for codes again and no codes found.
Hooked up the trailer and went to Indy. and back, 625 miles and still no codes. Had my fingers crossed the whole way.