Mine's a 2009 model.
TPMS light came on so I checked and filled all tires including the spare. They were all at around 33PSI except a couple at 30.5 so I filled all of them to 34PSI. I've driven over 300 miles since but the light is still on. I even tried disconnecting the battery for about 30secs but it's still on. Can someone help? Thank you.

 

One or more of your TPMS sensors' battery is flat, the next time you get your tires replaced the place that does it will tell you which ones are dead (don't forget to check the spare as well).

 

Is it possible for me to replace it? My tires are pretty new so I don't want to wait 'til the next replacement.

 

Probably not as you'll need to remove the tires from the rims in order to access the TPMS, and you can't just replace the battery, the entire sensor will need to be replaced.
Costco seems to do them affordably for $20/sensor (Toyota/Lexus will literally charge you an arm and a leg), but TBH when you put all the costs together it's a few hundred dollars (including labor), it's up to you if you think it's worth it vs ignoring the light.

Batteries in TPMS lasts about 7 years or so, but you should be checking your tire pressures at least:

- Once a month; and/or
- Before you head off on a long drive; or
- If there is a sharp dip in temperatures in a week

 

You can buy aftermarket pressure sensors from Amazon or You can bypass the TPMS module. My sensor started to die and to replace all five would cost more than $300. I bypassed the system and bought an aftermarket SYSTEM from Amazon rather than the aftermarket sensors because labor. https://www.clublexus.com/forums/es-5th-gen-2007-2012/705172-tpms-light-on-how-to-disable.html

[url=http://VESAFE Wireless Tire Pressure Monitoring System (TPMS) for small size 4-tire vehicles, including 4 external cap sensors (0-87PSI) [ame]https://www.amazon.com/dp/B01LA8LL12/ref=cm_sw_r_cp_apip_Uq33GMItk1rdy]VESAFE Wireless Tire Pressure Monitoring System (TPMS) for small size 4-tire vehicles, including 4 external cap sensors (0-87PSI) https://www.amazon.com/dp/B01LA8LL12/ref=cm_sw_r_cp_apip_Uq33GMItk1rdy[/ame]