I have had a lot of pain re these and bought a Low Tyre tester from OTC
OTC TPMS : Servicing Vehicles with Tire Pressure Monitoring Systems and it will allow me to test all my sensors and I can confirm that they are all on the same radio frequency and that this tool does test them and provide a reset with the magnet fitted (I assume the magnet activates the sender unit), I have used the DRB but from memory it only really performs an identical task, but I am not sure if each unit has an ID number as Dan described but in my opinion'He is the man'. But why would they all be on the same frequency, its not like the error tells you which wheel is flat??
If your low tire light is coming on at random then it is because the battery in the TPMS valve unit is going bad, I have just had Tator's supply me four new ones and I intend to get my kerbside front replaced as the OTC tester can not get a signal from it I will thern use the tester and reports back if it solves the problem or do I need a dealer and a DRB.
If you replace the TPMS valve it takes from 5-10 minutes of driving for the unit to be recognised and accepted by the receiver so if you replace the unit in the wheel , program it using the DRB the light will still be on until recognised.
You must also ensure that the box on the end of the valve is spaced equal to both sides, that could also mean it may not always work on all styles of wheels due to the valve to wheel rim location.
These are a pain in the butt and being in the UK took me a year to fix a faulty module.