Tank Level Display Not Reading Correctly

[2018 Duramax]

I have the same problem with my 2019 18RBE and have traced it to the vent height in the tank is to low. I first had the trailer leaning away from the fill side so I could get more water in it before the vent started to over flow. This gave me a FULL reading on the gauge. Once level of course the water started to run out the vent. I then plugged the vent so I could fill the tank completely FULL. Only problem with this is filling the tank as it wants to burp a lot so make this a slow fill. I then drained the tank and was able to lookup through the bottom drain dump. This is when I was able to measure the vent hole to the top of the tank. This confirmed that the vent is to low. I have a couple of ideas on how to fix this problem and will update the form once completed.

[harryc]

Maybe time to get a new dealer with better service department. My gauges on the fresh water and forward grey tank seem to read correct but the aft grey tank only reads 3/4 full when water is backed up in the sink. Most annoying. I had the sensors replaced under warranty by a local RV repair shop that dealt directly with Grand Design Service. Fully covered but the new sensors made no difference.

I just got my trailer back from getting warranty work done including checking/repairing the tank sensors. They were only reading 2/3 when the tank was filled to overflow. They flushed the tank to repair a leak in the dump valve then refilled it to check the sensor. It read full. There must have been some debris on the sensor that washed out when they dumped it. Maybe from drilling the hole for the sensor. Anyway, all good.

[2018 Duramax]

I just got my trailer back from getting warranty work done including checking/repairing the tank sensors. They were only reading 2/3 when the tank was filled to overflow. They flushed the tank to repair a leak in the dump valve then refilled it to check the sensor. It read full. There must have been some debris on the sensor that washed out when they dumped it. Maybe from drilling the hole for the sensor. Anyway, all good.

Harry please keep us updated on your service work on your tanks for only reading 2/3 full.

I can fill my take and some times it will read Full then goes to 2/3 with almost no water being used.
from my measurements the bottom of the vent hole is about 2 inches from the top of the tank on my trailer.
I'm also happy to hear you have a service dealer that will look after your trailer!
I'm not so lucky as my trailer was bought out of province as there were no trailers available when I was buying.
Dealers her only seem to look after their own customers.

I'm going to move my vent to the top off the tank and that will fix my issue as I always need as much water as possible when we are camping with no hookups.