Press the sauté button on the Instant Pot.
Add the olive oil and sausage and cook on sauté mode for about 5-7 minutes, or until the sausage is cooked through. (If desired, drain any excess fat.)
Pour in 1 cup of the water and stir, using your spoon to scrape up any browned bits from the bottom of the pot.
Pour in the marinara sauce and stir to combine well.
Add the uncooked pasta and push down gently to tuck the noodles into the sauce.
Pour the remaining cup of water over the top of the pasta, so it’s all covered.
Secure the lid and double-check that the pressure valve is set to sealing (not venting)
Press cancel to stop sauté mode, then press manual/high pressure and set the timer for 8 minutes. (It will take the Instant Pot about 8-10 minutes to come up to pressure.)
After it’s cooked for 8 minutes, carefully quick-release the steam by switching the pressure valve to venting.
When the floater valve has dropped, carefully open the Instant Pot lid and gently stir the pasta.
Feel free to stir in spinach or fresh basil or sprinkle with cheese to serve.