Why Are My RV Black Tank Sensors Not Working? How Do I Clean Them?

Why Are My RV Black Tank Sensors Not Working? How Do I Clean Them?

Posted by Happy Campers Store on Feb 2nd 2024

Why Are My RV Tank Sensors Not Working? Find All The Answers Here.

RV Holding Tank Sensors Are The Bain of Many RVers Happy Journeys, Leaving Many Travelers Simply Not Using or Trusting Them.

There are many reasons why your RV holding tank sensors might not be working and we're going to look at them all.

If you hate reading, here are your key takeaways from this post:

Why Are My Black Tank Sensors Not Working?

Why Are My Gray Tank Sensors Not Working?

Why Do My Black Tank Sensors Always Read Full? 

Black Tank Sensor Shows 2/3 Full When it's Empty?

Black Holding Tank Sensors Always Read 1/3 Full?

The answer to all of these questions is almost always due to a buildup of residue and solids in the tank. This post will show you how to assess the issue, clean the sensors to get them working again, or whether you need to replace them.

How Do I Test My RV Tank Sensors to See if They Need to Be Replaced?

This is a simple 4-step process, click to view them!

What Type of RV Holding Tank Sensors Do You Have?

  • Through-wall/probe sensors are the most common RV tank sensors and the most likely to fail. The probes extend into the tanks to measure the electrical conductivity between them and the water. The problem is, if anything gets between the water and the probe — you're not going to get an accurate reading.


  • What types of things prevent your sensor from reading correctly?
    The most common obstructions are; human waste, toilet paper, grease, oils and soap scum buildup.


  • How do I know if my sensors need to be replaced? 
    Traditional RV holding tank sensors have long been plagued by accuracy issues. Follow these simple steps to determine if your sensors need to be replaced; 
    • Rinse and clean tank.
    • Clean Tank with chemical treatment to remove any buildup or soap scum.
    • If issue is resolved, maintain your tank with a treatment to prevent buildup and enjoy your travels.
    • If the issue is not resolved, it might be time to upgrade your holding tank sensors. (Don't worry. It's not as bad as it seems.)


This post provides an overview of different types of RV holding tank sensors, common reasons for their failure, maintenance techniques, selecting the right soap for tanks, advanced solutions for reliable readings, and professional help for stubborn sensor issues.

How Do I Clean My RV Holding Tank Sensors?


Image Source:  Amazon Extreme Cleaner Customer Upload


Overview of RV Holding Tank Sensors

RV holding tank sensors are essential components of the RV's waste management system, providing crucial information about the levels of fresh water, gray water, and black water tanks. Well, at least they should...

Accurate sensor readings are vital for effective maintenance and convenience during camping trips. However, these sensors are prone to various issues that can lead to failure and inaccurate readings, impacting the overall functionality of the RV holding system. Sensor issues are probably the most common annoyance that RVers face.

Understanding the common types of RV holding tank sensors and the reasons for their failure is essential for maintaining a trouble-free camping experience.

For instance, consider a scenario where an RV owner relies on the sensor readings to monitor the gray water tank levels. If the sensors are not functioning correctly due to build-up or malfunction, it can lead to unpleasant surprises, such as standing in gray water while showering. A situation like this highlights the significance of accurate sensor readings for ensuring a hygienic and comfortable camping experience

If you're dealing with sensor issues, this post will cover the different types of RV holding tank sensors and the factors contributing to their failure as well as how you can correct them.

How Do RV Holding Tank Sensors Work?

Through-Wall/Probe Sensors

Through-wall/probe sensors are among the most prevalent types of RV holding tank sensors. They operate by using small metal nubs, or probes, that extend into the tanks to measure the electrical conductivity between them. While these sensors are cost-effective, they are susceptible to gunk build-up, leading to false readings and unreliable performance.

For instance, a study by TheRVGeeks highlights that through-wall/probe sensors are chosen by RV manufacturers based on cost, making them a common inclusion in many RV models. However, their susceptibility to gunk build-up and false readings underscores the need for RV owners to be aware of the potential issues associated with these sensors. By understanding the operational characteristics and limitations of through-wall/probe sensors, RV enthusiasts can make informed decisions regarding the maintenance and upkeep of their holding tank sensors.

External Electrical Resistance Sensors

External electrical resistance sensors offer an alternative to through-wall/probe sensors. These sensors are mounted on the exterior of the tanks and utilize electrical resistance to measure the tank levels. They present advantages over through-wall/probe sensors, as they are less prone to false readings, thanks to their placement outside the tank. However, they come with a higher price tag, making them a less common option in RVs.

Research from TheRVGeeks suggests that external electrical resistance sensors provide a more reliable solution for monitoring tank levels due to their reduced susceptibility to false readings. While their initial cost may be higher, the long-term benefits of accurate sensor readings and minimal maintenance requirements make them an attractive option for RV owners seeking dependable holding tank sensors. Understanding the operational mechanics and advantages of these sensors can help RV enthusiasts make informed choices when considering sensor upgrades or replacements.

External Acoustic Sensors

External acoustic sensors represent a more advanced type of RV holding tank sensors. These sensors utilize ultrasonic technology to provide precise percentage readings of the tank levels without direct contact with the tank contents. While they offer more accurate readings, they are also the most expensive option, making them less common in RVs.

Insights from TheRVGeeks shed light on the enhanced capabilities of external acoustic sensors, highlighting their ability to provide exact percentage readings and minimize the risk of false readings. Despite their higher cost, their superior accuracy and reliability make them an appealing choice for RV owners who prioritize precise monitoring of their holding tank levels.

Why Do RV Holding Tank Sensor Fail?

RV holding tank sensor failure can occur due to various factors, impacting the accuracy and reliability of the sensor readings. One common reason for sensor failure is the accumulation of sludge and the development of struvite crystals, which can interfere with the sensors' ability to provide accurate readings. Additionally, the use of certain soaps and chemicals can significantly impact sensor performance, causing misreading due to obstructions. Therefore, understanding the reasons for sensor failure is essential for implementing effective maintenance strategies and preventing potential issues.

Research from AskKleenTank emphasizes that the build-up in black and gray holding tanks is caused by tank additives dissolving the tank’s contents into a thick, sticky slurry. This build-up can lead to sensor malfunction and inaccurate readings, highlighting the importance of using compatible tank additives and cleaning products to mitigate these issues. By addressing the common reasons for sensor failure, such as sludge build-up and chemical interference, RV owners can proactively maintain the integrity of their holding tank sensors, ensuring accurate and reliable performance.

How Do You Clean RV Holding Tank Sensors? 

Prior to spending hundreds of dollars to have your tank sensors professionally cleaned or upgraded try this:

Happy Campers Extreme Cleaner stands out as a versatile and powerful solution for maintaining clean and odor-free holding tanks in RVs. Its specialized formulation is tailored to effectively address the unique challenges associated with cleaning black and grey tanks, providing a comprehensive cleaning solution for RV owners.

One notable benefit of using Happy Campers Extreme Cleaner is its exceptional ability to remove stubborn waste, tissue, soap, and scum buildup in holding tanks. Here's what you should do:

1.Prepare Your RV Holding Tanks

Before using Happy Campers Extreme Cleaner, pre-charge the tanks with water and ensure they are ready for the cleaning process. It is also important to use disposable gloves and follow recommended safety measures before application.

2. Mix and Apply the Tank Cleaner

Follow the prescribed dosages provided by the manufacturer and mix the cleaner with hot water as per the tank size [2]. Carefully pour the solution down the sink or flush it down the toilet to ensure even distribution within the tanks. After application, drive for the recommended duration to facilitate the cleaning process before dumping and rinsing the tanks.

3. Tips for Preventing Sensor Buildup

To prevent sensor buildup and eliminate odors, it is advisable to regularly treat the tanks with a product like Happy Campers Holding tank treatments. Additionally, using recommended toilet tissue brands can minimize residue and maintain sensor accuracy. It's important to avoid using bleach or home remedies and ensure proper maintenance to prolong sensor lifespan.

4. When to Use Happy Campers Extreme Cleaner

The extreme cleaner is intended for deep cleaning to address stubborn buildup or mold, rather than as a regular maintenance treatment. Annual or as-needed use of the product is recommended based on the condition of the tanks and sensor performance.

I've tried everything and...

Do I Need to Replace My RV Tank Sensors?

How Do I Know If My RV Tank Sensors Need to be Replaced? 

Decoding the Signs: When to Replace Your RV Tank Sensors

When you've tried all the standard solutions to get your tank sensors working ie: rinse, clean, chemical treatments, etc. then it might be time to replace your tank sensors.

Are you still experiencing any of these issues after using a cleaning agent?

1. Inaccurate Readings: 

One of the most common signs of a failing RV tank sensor is inaccurate readings. If your sensors are showing that your tanks are full when they're not, or vice versa, it might be time to replace them.

2. Consistently Full Readings: 

If your sensors are consistently showing that your tanks are full, even after you've emptied them, this could indicate a problem with the sensors.

3. Erratic Readings: 

If your sensor readings are fluctuating wildly without any corresponding changes in your tank levels, this could be a sign of failing sensors.

4. No Readings: 

If your sensors are not providing any readings at all, this is a clear sign that they need to be replaced.

How to Replace Your RV Tank Sensors

If you've determined that your RV tank sensors need to be replaced, here's a basic guide on how to do it:

1. Purchase New Sensors: 

Start by purchasing new RV tank sensors. Make sure to choose high-quality sensors that are compatible with your RV's system.

2. Remove the Old Sensors: 

Next, remove the old sensors from your RV's tanks. This process will vary depending on your RV's model and the type of sensors you have, so refer to your RV's manual or consult with a professional if you're unsure.

3. Install the New Sensors: 

Install the new sensors in your RV's tanks. Again, the process will depend on your RV's model and the type of sensors, so refer to the instructions provided with the new sensors or consult with a professional.

4. Test the New Sensors: 

Finally, test the new sensors to ensure they're working correctly. Fill and empty your tanks a few times and check the sensor readings at each stage to ensure they're accurate.

What RV Tank Sensors Should I Use?

Sea Level RV holding tank sensors offer a multitude of benefits over traditional sensors, making them a popular choice among RV enthusiasts. One significant advantage is the improved accuracy in providing tank level readings, which effectively addresses the common inaccuracy issues experienced with traditional sensors. Another premium benefit is the cost. You can pick up this easy to install system from RV Upgrades for only $234.95.

SeaLevel 2 Tank Monitor from RV Upgrades

How to Install Sea Level Tank Sensors:

Why Do We Like SeaLevel RV Tank Sensors So Much?

Sea Level sensors are designed to be resistant to corrosion and buildup, ensuring that they consistently deliver accurate readings over time. This resistance to deterioration is a crucial feature that sets them apart from traditional sensors, which are prone to malfunctions due to the accumulation of residue on the probes. By maintaining their accuracy and reliability, Sea Level sensors offer peace of mind to RV owners, allowing them to trust the information provided by the monitoring system without concerns about potential errors.

In addition, the compatibility of Sea Level RV holding tank sensors with various tank shapes and sizes enhances their appeal. This versatility caters to different RV setups, accommodating the diverse tank configurations commonly found in recreational vehicles. Whether it's a large, irregularly shaped tank or multiple smaller tanks, Sea Level sensors offer a solution for accurate monitoring, making them a practical choice for RV owners with distinct holding tank requirements.

Furthermore, aftermarket sensors like SeeLevel RV Tank Sensors offer a reliable solution for more accurate readings on tank levels. These sensors are designed to minimize the risk of waste and grease sticking to the sensors, which can cause misreads.

By exploring advanced sensor options, RV enthusiasts can gain valuable insights into potential solutions for enhancing the accuracy and reliability of their holding tank sensors, mitigating the impact of common reasons for sensor failure and improving the overall functionality of their RV waste management system.

Maintaining RV Holding Tank Sensors

Regular maintenance of RV holding tank sensors is crucial for preventing failure and ensuring accurate readings. Cleaning techniques such as using a tank cleaning wand, dishwasher detergent, and good tank cleaner can help in removing build-up and maintaining sensor performance. These cleaning methods are effective in addressing issues caused by sludge build-up and gunk accumulation around the sensors, which are common reasons for false readings.

In addition to these cleaning techniques, professional power washing and calibration play significant roles in sensor maintenance. Power washing offers an advanced solution for removing stubborn residue and build-up that may affect sensor accuracy. Calibration allows adjustments to be made for more accurate readings, ensuring that the sensors provide precise information about the tank levels. By incorporating these maintenance practices into their routine, RV owners can prolong the lifespan of their holding tank sensors and minimize the risk of sensor failure, contributing to a more reliable waste management system in their RVs.

Moreover, understanding the role of professional cleaning services, such as those offered by Kleen Tank LLC, can provide RV owners with additional options for maintaining their holding tank sensors. Kleen Tank LLC's mobile service and hydrojetting technology have been proven to effectively address stubborn sensor problems, offering a chemical-free and all-natural solution for tank cleaning. By leveraging professional services and advanced cleaning techniques, RV enthusiasts can enhance the performance and longevity of their holding tank sensors, ensuring the accuracy and reliability of the waste management system in their RVs.

Selecting the Right Soap for RV Holding Tanks

When it comes to maintaining RV holding tank sensors, selecting the right soaps and tank additives is crucial for preventing sensor problems and failure. Using the wrong products can lead to sensor issues, ultimately impacting the performance of the waste management system in the RV. Therefore, understanding the guidelines for selecting tank-safe products and the impact of using harmful additives on sensor failure is essential for RV enthusiasts.

Insights from Unique Camping + Marine emphasize the importance of choosing tank-safe products, such as biodegradable soaps and detergents specifically designed for RV holding tanks. These products are less likely to leave behind residues that could interfere with sensor readings, contributing to the longevity and reliability of the holding tank sensors. By making informed choices about the cleaning and maintenance products used in RV holding tanks, owners can significantly reduce the risk of sensor issues and ensure the proper functioning of their waste management system [3].

Additionally, these research sources provide valuable information about the impact of using harmful tank additives on sensor failure. For instance, AskKleenTank highlights that certain tank additives can lead to build-up and corrosion, causing erratic sensor behavior and inaccurate readings. 


          A huge RV no-no is using bar soap to wash your hands or body. Bar soap, unlike most liquid hand soaps, leave a thick layer of soap scum in your gray holding tank. One shower with a bar soap will impact your sensor readings!


You will find many posts online that recommend using a degreaser to remove bar soap scum, but you will find, like so many of our customers, that most enzyme based treatments and degreasers won't remove bar soap scum. For this, you will need an actual soap scum remover - not a degreaser.

Therefore, by avoiding harmful tank additives and selecting compatible products, RV owners can proactively maintain the integrity of their holding tank sensors, minimizing the risk of sensor failure and ensuring the accuracy of the waste management system in their RVs. These insights underscore the significance of making informed decisions when choosing soaps and tank additives for maintaining RV holding tank sensors.

Professional Help with Stubborn Sensor Issues

When dealing with persistent RV holding tank sensor issues, seeking professional assistance can provide effective solutions for addressing stubborn problems. Kleen Tank LLC is one such company that offers mobile services and utilizes innovative hydrojetting technology to effectively tackle sensor issues. Their chemical-free and all-natural solutions for tank cleaning have been known to restore sensor functionality, offering RV owners a reliable option for maintaining their holding tank sensors and ensuring a trouble-free experience on the road.

The extensive experience of Kleen Tank LLC, as showcased in their track record of cleaning over 6,000 holding tanks in various RVs, highlights the effectiveness of their services in addressing a wide range of sensor issues. By leveraging the expertise of professionals like Kleen Tank LLC, RV enthusiasts can benefit from innovative solutions for maintaining the accuracy and reliability of their holding tank sensors. These professional services offer a valuable resource for RV owners seeking effective remedies for stubborn sensor problems, contributing to the overall functionality and performance of the waste management system in their RVs.

Moreover, insights from AskKleenTank provide additional details about the capabilities of Kleen Tank LLC, emphasizing the effectiveness of their mobile service and hydrojetting technology in correcting sensor issues. By understanding the role of professional cleaning services and advanced technologies in addressing stubborn sensor problems, RV enthusiasts can explore additional options for maintaining the integrity of their holding tank sensors, ensuring accurate and reliable performance during their camping adventures. These insights underscore the value of professional assistance in mitigating persistent sensor issues and enhancing the overall functionality of the waste management system in RVs.

Conclusion: Importance of Proper Maintenance for RV Holding Tank Sensors

Maintaining the performance and reliability of RV holding tank sensors through regular cleaning, calibration, and the selection of tank-safe products is essential for preventing sensor issues and ensuring accurate readings. By proactively addressing common reasons for sensor failure, such as sludge build-up and chemical interference, RV owners can maintain the integrity of their holding tank sensors, contributing to a trouble-free camping experience. These maintenance practices offer a proactive approach to mitigating potential sensor issues and improving the overall functionality of the RV waste management system.

If maintenance measures are no longer an option then you'll want to seek advanced sensor options and leveraging professional assistance. We at Happy Campers Store highly recommend trying the  Extreme Cleaner as an effective and cost saving alternative prior to forking over $800 for a professional cleaning. 

Hopefully this post has provided valuable insights into potential solutions for enhancing the accuracy and reliability of your holding tank sensors, ensuring a more enjoyable and stress-free camping experience. 

RV holding tank sensor failure is common and it's just a matter of time before you experience it for yourself.