- Only for testing engine systems.It cannot erase private codes including: airbag, ABS, TPMS, or oil change lights etc.The error that causes the error code to display must be repaired before the code can be removed. - When using this device to check the vehicle, make sure the engine is in starting condition, otherwise there will be no data flow or error code. -If your vehicle has some wrong things, you need to go to the garage to resolve the wrong things.And then clear the error codes after repair. -Compatible with most cars from the year 2002 but in different regions the valid time to support the vehicle's OBD2 protocols is different.Or some car is specially designed so it may not support the vehicle's OBD2 protocols. -It can support all 12V gasoline and diesel vehicles, but not for 24V heavy duty vehicles, hybrid or electric vehicles.