Originally Posted by Boxster1971
The LP tank gauges are notoriously unreliable, ...
We replaced our LPG tank last year and the danged gauge still doesn't work properly despite being newly installed and newly wired. I never know what we have in the tank.
I noticed in our local RV repair place that they have external ultrasound gauges for sale right next to their cash register, suggesting that it's an item that many customers request. They were similar in design to this Truma Level Check gauge
and they were not cheap. I don't know if they work. Even if they did, with an Interstate, it would require crawling under the chassis and with a horizontal rather than vertical cylinder, I'm not sure how accurate they would be.