Black tank sensor

Tom Ficca · 07-03-2022, 12:37 PM

I have a 2018 Forza 38F and I cannot get the black tank sensor to zero out . I have flushed it so clean I could use it for a fresh water tank . Is it possible I have a bad set of stick on sensors ? It will only show 67% full after empty and 5 or 6 rinses . Any help would be great ! Thanks !

**macnut** · 07-03-2022, 04:30 PM

I have the same issues and was told to use this: Unique Sensor Cleaner Liquid for... https://www.amazon.com/dp/B0741NL8S5...p_mob_ap_share
I will let you know how it does.

CapeCodRob · 07-10-2022, 11:54 AM

Interested in how this turns out. We have a 2019 Forza 38F and have issues, with the black tank readings. Ours does show zero after a dump/flush but shows full within 2 days of normal use by 2 adults. I’ve found that we can go another 2 days or so before the Tecma toilet will show “red” indicating the tank is full. Are the sensors in different locations or is it electrical?

By comparison we would get at least 6 days out of our Bounder Diesel before needing to dump.

BobC · 07-10-2022, 06:25 PM

I gave up on my black tank sensors a long time ago. I just check the level via the toilet with a flashlight.

**macnut** · 07-10-2022, 08:56 PM

Quote:

Originally Posted by macnut

I have the same issues and was told to use this: Unique Sensor Cleaner Liquid for... https://www.amazon.com/dp/B0741NL8S5...p_mob_ap_share
I will let you know how it does.

I tried it and it still shows 2/3 full after emptying. However, I didn’t follow instructions closely and just added it about 8 hours before emptying, so I think I have to try it again before passing judgement.

thompwil · 07-11-2022, 07:44 AM

Howdy,
This is worth a try if you have the stick-on sensors. The stick-on sensors are capacitive type and were way too sensitive on ours too, capacitive as used in electronics terms not tank capacity. This fix worked to my satisfaction.

· Carefully remove the sensors after marking where they are mounted on the tank. I made a little saw using fishing line.
· Remove all the sticky adhesive tape from the back of the sensors until clear of all residue.
· Apply 3M automotive double stick tape to the back of the sensors, make sure to cover the entire sensor with the tape.
· Reapply the sensors to the tank.

The 3M tape appears to be slightly thicker than the factory tape and spaces the sensor slightly farther away from the tank. Ours now work to my satisfaction, sometimes the gray tank will take an hour or so to settle down to zero after a dump depending on how much cooking grease was inadvertently run down the sink, but it will zero out. Black tank is good with the exception of the occasional paper stick to the side of the tank which also goes away in a short time. I had considered trying two layers of double stick tape, but its working good enough to not be annoying so I haven’t bothered yet.

dennysbabe · 07-11-2022, 10:15 AM

Our 2008 Sightseer sensors seem to be stuck. The bottom (E) light is on as well as the 2/3 light. The 1/3 and Full lights never come on and we have definitely had it full. Any ideas how to fix that?

deckape · 07-13-2022, 04:51 PM

When we got our Forza I tried anything I could to clear sensors . Calgone , Borax ,chem cleaners etc .. .. Finally stayed with borax and water . Before leaving for a trip I clean both tanks completely . Add borax to both and add several gallons of water . Let that wash while I travel ,camp and then dump . Do it again . I find that traveling washes the tank clean . If worried about tank having water in it , just dump that water before hooking up . Most sites we use have a sewer hookup .

eaglelen · 07-13-2022, 06:42 PM

Had the same issue. Filled both tanks with clean water. Added 1 cup borax and 1 cup dawn. Let it sit for a week. Dumped and flushed. Sensors now working fine. 2019 Adventurer 35F.

1237dmctlc · 07-13-2022, 10:04 PM

Most people have had Tank sensors problems, one time ir the other for all types of an RV. The ones we've owned always seem to have problems including our current MH. It's usually the black tank for most folks but I've had both. I've flushed them out added calgon, dawn etc. It works for a while then it's back. Its the nature of the beast. I'm sure some folks might have ways that might work but I've just not found one that last. I heard to add bags of ice fill the tank and drive around a while but you need to make sure it all melts before you drain it or it could clog the drain. So let us know if anything works.thxs

**creativepart** · 07-14-2022, 08:03 AM

I’m not trying to be a smart guy posting this just reporting… we never have had any issues with our tank sensors - fresh, gray or black on our Adventurer. Since we used to on other RVs, I figured Winnebago had this mostly figured out. So, I’m surprised so many are reporting so many problems - even Macnut that has the same model and year as mine.

I do wish the sensor was more usable, 1/3rds is really no help at all.

I have clear easy access to my fresh tank and one of these days I plan to mark the outside of the tank in 10-gal increments.

If I ever get a catalytic converter for it so I can use it again that is.

GotUr6 · 07-14-2022, 09:46 PM

We have an ‘18 Forza 36G and had the same problem. A mobile RV service friend recommended this. Fill the tank full of water. Then use a half bottle of Dawn liquid dish
Washing detergent and a half bottle of LIQUID Cascade dish washing detergent. Let it sit over night then drain and flush. It worked like a champ. We have had one other time the sensor was covered, did this again and have had an issue in over 18 months.