Has anyone had to troubleshoot an OPn code (Open Circuit) on their blank tank? I have a 2019 Unity Rear Twin Bed and I am not sure where the Blank Tank is? Which one and where are the wires from the sending unit in relation to vehicle landmarks underneath the coach?
Have a 2019 24MB and the tank is in front of the rear axle. I had a broken wire to the sender and had to replace the sender. Not a big issue if you want to do the work yourself. I had to clean the undercoating off the old one and remove it then clean the area with mineral spirits.
Buy a new sender and cut to length and stick on. ( go to RVupgrades.com for info) and wire it up. Make sure the wire doesnt dangle so it can get pulled off again. I just used zip ties to secure it to something down there.
Good luck.
Sorry, I replaced the fresh water sender not the black. Once you find the black tank it should be the same. I did a post earlier the forum that might have more information.
Good luck