Wish I had an active subscription, I would help you out. Otherwise, you can sign up for a 1 month subscription here for just $20 and get all the diagrams/instructions you need.
https://www.alldata.com/diy-us/
I would figure out a way to check the sensor, or the reductant level sensor may be malfunctioning or damaged, causing the P203E code to be triggered. Inspect the sensor and wiring for any signs of damage or wear.