What is Purpose of Screws of Replacement O-Rings for TST 507 Series TPMS Sensors for RVs

Updated 02/16/2026 | Published 02/09/2026

Question:

What are the 18 screws for?

asked by: Ty

Expert Reply:

The screws are there to be replaced when you replace the gasket or perform any maintenance on your sensor.

expert reply by: Jameson C

Jason

2/13/2026

The screws hold the outer shell on the sensor. The shell helps with weather and security (why the wrench is needed). The screws are small and should be replaced when you change the battery as they are likely weathered. If you don’t see the screws your outer shell ma be missing or a different model.

Jameson C.

2/16/2026

@Jason thank you! Is the screw on the side of the sensor by chance? I looked in our pictures of the sensors and wasn't able to find any but maybe it was all the wrong angle in the picture.

John T.

2/13/2026

The screws are replacements for the originals in the cap sensors. Mine were pretty rusty after 10 years. Each sensor has 3 screws holding the outer shell on which is there to prevent the sensors from being taken off without the proper tool. BTW they give you extra screws over the 12 required.

Jameson C.

2/16/2026

@JohnT good to know!

Jameson C.

2/16/2026

@JohnT good to know!

Charlie Z.

2/13/2026

There are two different sensor types, cap and flow through. I have the cap style sensors and have purchased the O ring kit. I don't recall receiving any screws with the kit and screws are not required/used for the cap style sensor. Can't speak to the flow through.

Wally O.

2/13/2026

Yep, the screws are there to be replaced when you replace the gasket or perform any maintenance on your sensor. if you have a question about the O-rings, they did not work for me and I ended up having to buy a brand new sensor.