The Thexton Professional DEF Tester, No. 108, is a Diesel Exhaust Fluid (DEF) tester that features urea concentrate testing and temperature compensating discs that test hot or cold DEF. If the mixture is 0.7 percent off, the manufacturer suggests replacing DEF and identifying why the concentrate is off. If the DEF concentrate is not correct, the injectors may become clogged and the DEF will not work properly.
