TPMS sensors
 

Hi Guys,

I realized the 2014 BRZ im getting pre-owned has aftermarket wheels.

I dont know how the TPMS sensor system works but form what i've read, aftermarket wheels would make it light up the dash and you have to re-program.

I am assuming for now, the owner probably had someone turn it off and kept the stock rims and sensors. But I plan to revert the car back to all stock even wheels. How do I go about this?

Do I ask him up front, "how did you manage the TPMS sensor after swapping tires? did you keep the stock sensors?"

And is it as simple as going back to another wheel shop, handing them over the stock wheels and sensors to reinstall again?

Thank you!

Aftermarket wheels without having a TPMS sensor would make it light up. If you find a set of stock wheels and sensors you will have to get them programmed for your car. I believe you can do this yourself with Toyota Techstream. The cable to do so is around $25USD.

Hi sir! The owner did mention that he kept the stock wheels so i assume stock sensors are there too right? Just not sure what to ask and expect when i meet him.


Sent from my iPhone using Tapatalk

I can't answer that question, you would have to ask the owner. If the wheels still have the stock tires on them I would assume that the TPMS sensors are there. It would have cost more to unmount the stock tires from the stock wheel and put the TPMS sensor on the new wheel and tire, most people would opt to leave them off for the sake of saving money.

I believe this was indeed the case as the new wheels have dunlops on them.
So basically, the TPMS sensors are little devices attached to the tires, and he could have placed them on old/new tires, but point is i will need to bring it by a shop to have reprogramed when i install old tires again?

You're pretty much correct. TPMS sensors are mounted inside of the wheel.

Thanks for the help sir!

You won't need to have them reprogramed. Once they are back on the car the sensors will just grab them again. Mine stay on my summer tires for 4 months a year while I run winters without them and they just kick back in after a few miles when I swap back.

I had an odd thing happen with my 2013 BRZ. I bought a whole new set of tires and rims from Tire Rack along with the recommended TPMS sensors. Long story short, could not get the car to read them. The dealer tried twice as well as my friend's tire shop. Luckily I keep the stock tires. After going back and forth Tire Rack agreed to pay for me to swap them with the sensors in the stock tires and return the ones I bought.

Here is the strange part. When they removed the sensors in the new tires, they were the same exact make and models of the ones in the stock tires. Exactly the same. Yet the car would not read them. So after putting the original sensors back in bam, they worked! The dealer had no problem re-syncing the original sensors. So no idea why that happened, puzzling???

Don't know if our sensors have batteries but we had that same issue with my 2012 Lancer. We could not get the damned TireRack sensors to work no matter what we tried. Pulled a tire to check the installation and all looked good. Then the Service manager comes out and pulls the little plastic strips that separate the battery from the contactor out and Bingo!

On my tribeca so I would assume the brz is similar....Each sensor has a hex address that needs to be programmed into the body control module.

New sensors are 'asleep' and must be activated to conserve the battery. This can be accomplished before or after installation. The address is labeled on the sensor or it can be read electronically.

Once activated and synced, some sensors ping every 90 seconds and/or are activated by the car moving more than X miles per hour.

Assuming Subaru uses valve stem type TPMS sensors they have internal non replaceable batteries. The service life is not known with certainty but is thought to be about 5-7 years, coinciding with expected tire life (nobody should be running tires that are over 7 years old).

They are shipped in dormant or hibernating state to maintain this service life from date of activation. Different TPMS software activates these sensors differently. Some self activate and some require activation codes to be inputted to the TPMS ECU.

Self activating sensors respond to pinging from the TPMS ECU and wake up after a few pings. That's how the sensor and ECU communicate from then on. The codes are different for each sensor in order that the TPMS ECU detects which corner the wheel is on and that combo of sensor code and TPMS code follows that wheel until the code is overwritten by a new sensor install. I know for sure the TPMS ECU can store at least 8 codes and probably more before it will forget a code.

Garage door openers have a similar memory (different coding system) which can fill up if you have programmed too many homelink codes into the same receiver over time. These have an internal code clearing system. I discovered this during a particularly frustrating homelink coding session with a newly acquired car.

If you have trouble with TPMS not activating then perhaps the correct wake up call has not been sent or perhaps your car has had three sets of TPMS equipped wheels installed and the TPMS ECU needs to be cleared. I do not know if Subaru TPMS has a maximum memory capacity for codes but I suspect it might.

I installed my rims a couple months back and the light has been flashing every day since, I don't even notice it lol. I'm supposed to take the car in to get them programmed but I'm too lazy.

Replacing valve stem type TPMS should not be expensive. The repair shop just needs to break one bead, remove and replace the valve stem and reseat the bead. Make sure the shop knows the correct install torque. It is given in inch pounds, overtorquing is the number one cause of leaking TPMS valve stems.