Hi, I have a 2019 Freightliner Cascadia. With a Detroit DT12 engine. There is a yellow engine light on in the left side of the dashboard. No dash codes. Could this be DEF related? Or something else all together. See attached picture. Thank you.
Oh. I see. You’re talking about yellow one under tachometer, right?
There’s menu with wrench symbol on dashboards screen. Use right and left buttons on the left side of the steering wheel to get there. It has diagnostics menu. Check what error is it. Youtube link.