Advice, Reocurring Chk Eng Lgt & DDEC Report Issues w Frlnr Casc

Hi everyone,

I'm reaching out to the community for some advice and guidance regarding an ongoing issue I've been facing with my 2019 Freightliner Cascadia, equipped with a DD13 engine and DT12 transmission. I bought this semi-truck from Select Truck of Houston with 234,000 miles on it. It seemed well-maintained at the time of purchase. However, I've encountered a recurring problem that I'm hoping to get some insights on.

While driving from Houston to Odessa, where I plan to work hauling fracked sand, the truck threw a check engine light and a fault code related to the after treatment system. After resting for the night, I found the truck derated to 5 mph the next morning. I took it to a Freightliner dealer in Odessa, and they identified an issue with a nox sensor. The repair was covered under the $13,000 warranty I had purchased for two years. Three days post-repair, the check engine light appeared again. The truck was in the shop for two days before I got it back. However, four days later, the check engine light came back on, and now the truck is back at the dealer.

During their diagnostics, they pulled DDEC report and found idle percentage at 78% life to date. I'm not entirely sure what my next steps should be and am looking for advice on how to proceed. I am feeling they sold me a lemon at Select truck of Houston. The truck has a 90 days buyer assurance warranty and a basic and max Freightliner warranty for 2 years/250K miles.

Has anyone here experienced something similar with their truck? How did you resolve it? Any advice on dealing with the dealership? Also, how concerning is the idle time at 78% in the DDEC report? I'm relatively new to this and greatly appreciate any insights or guidance you can offer.

Thank you in advance for your help!