In Focus: Thexton THX108 DEF-CHEK Professional Tester

The Thexton THX 108 DEF CHEK Tester is a diesel exhaust fluid (DEF) tester that features urea concentrate testing and temperature compensating discs that test DEF, hot or cold. If the mixture is 0.7 percent off, the manufacturer suggests replacing DEF and identifying why concentrate is off. If the DEF concentrate is not correct, injectors may become clogged and DEF will not work properly.

Key selling points

  • The product tests urea concentration in the DEF tank of heavy duty vehicles.
  • The tester helps avoid costly repairs.
  • Temperature compensating discs test DEF hot or cold.
  • Failure to test the urea will result in lost performance in the vehicle.

Features and benefits

The THX 108 DEF CHEK Professional Tester provides the diesel vehicle (car, truck or heavy-duty vehicles) the ability to check the DEF tank in a cost-effective manner.

The tester is an accurate measurement tool to test the urea content in the vehicle’s DEF tank.

The product works with any vehicle that has a DEF tank installed.

In 2009, the EPA mandated that all diesel vehicles 2010 and newer be required to have a DEF tank installed.


The THX 108 DEF CHEK Professional Tester is used to check the urea content in the vehicle’s DEF tank. The tester will provide technicians with a cost-effective way to test the urea content.


The THX 108 DEF CHEK Professional Tester is manufactured in the USA. The product is constructed of a plastic tube, polypropylene plastic disc and rubber top. It allows for testing of the urea content in the DEF tanks on diesel vehicles. The product weights less than 2 lbs.

Storage and display

The THX 108 DEF CHEK Professional Tester is packaged in a see-through, shrinkwrap package. Hang the THX 108 on display in the tool truck or bring it inside at stops to show shops that work on diesel vehicles.

Suggested retail price


For more information

For more information, contact Peter Swenson, vice president of sales and marketing, or Ross Tichy, vice president of product development at Thexton Manufacturing Co. Phone: (800) 328-5938; email: or