Digital Tire Preure Monitoring System TPMS 1: What's the differenc between direct TPMS and OBD TPMS ? There are two types of TPMS systems: direct TPMS and indirectOBDTPMS. A:Direct TPMS systems use TPMS sensors inside the wheel to report preure data to the vehicle's ECU in real time. 2: IndirectOBDTPMS system uses an ABS system to monitor the speed of the wheel and communicate to the ECU. 3: Direct TPMS show the true preure value , OBD TPMS showsanalog value. 2: What is theadvantageof OBD TPMS ? 1. No need to disaemblycar wheel , just connect to OBD plug . 2. Noneedreplace battery. 3. Some car model with fatigue drivingremindand locking function . ( Outlander without locking function) 3: What is the data 2.4 , 1.8 mean ? 2.4meansnormaltire preure . 1.8 meanstire preure leak up 20%-25% 1.0 meanstire preure leak up 50% or more 4: Can the data change to PSI or Bar ? It can not change to psi or bar because it work without sensor , the value on screen is aanalog value. 5: Is it need setup before using ? Yes , it need a learning proce after install it . We include user manual of how to use it . Notice: Don't stop car test, it can't test the tire preure if stop the car to test.