diagnosing TPMS - DIY?

My 2012 highlander has a constant light but no air leaks. Failed sensor I suspect. Not the kind that monitors each tire - just a general light. I have an OBD reader but just basic type.

Are these sensors user replaceable or is it best to pay the man?

Testing:

• Get a copy of Techstream and VXDiag cable - the cheaper cables can not write to the TPMS module in most Toyotas. 
• Read the TPMS codes, determine which sensor needs replacement by letting air out of the tires 1 at a time and seeing which one(s) don't work/report the pressure change in techstream.  Its usually pretty fast, within a minute or less.  Do one at a time.

Once you determine the bad sensor(s)

• Remove the wheel from the vehicle and break one bead with a floor jack (youtube videos for this)
• Press the bead down near the TPMS and remove it from the rim
• TAKE A PICTURE OF THE CODE OF THE NEW TPMS
• Install the new TPMS, air up the tire, reinstall it.
• Air up all the tires to the pressure listed on the B pillar sticker.
• Write the new code in place of the code of the defective sensor using Techstream.
• Light should go off, take a short drive to confirm

Thats the easiest way I have found to do it at home without many specialized tools.  The VXDiag cable and techstream are super helpful and around $100. 

Pay the man.  

Every car that hits the 10-12 year mark with original sensors gives me trouble.  If one is bad the rest will follow. You do know there is a battery inside the sensor.

Discount Tire was $60/wheel and I replaced all four in the daughters car since she is 300 miles away at college.  Now it all works perfectly.  

Shop around - Wally World was $35 but hadn't had replacements for 3 months.  One guy told me $100....a tire....

Always more to learn here. Not disappointed. Thanks

some Toyota's have a tpms in the spare, check the pressure in it, if it was low do a 5 tire relearn, 

and then recheck it by doing a couple drive cycles