You are putting a lot of “faith” into the “Jaco” gauge. Get a simple “stick” pressure gauge and keep it in the glove box…use that to check the pressures and compare them with the readout. People lived quite happily with the simple gauge for decades…they work. Don’t be obssessed with a small, 1 or maybe 2 psi difference between the simple gauge and the car gauge. If need be, compare the Jaco with the simple gauge as well. It is normal to see small differences between gauges…they are not precision, scientific instruments. Look for patterns…front right, back left, etc. Right now mine read 35 back left, 37 front right, 36 front left, 36 back left….no big deal, not worth my time to try to make them “perfect”. 30 minutes on the highway and the relative differences between tires will change. Drive on.

 

I like the Jaco gauge because it measures pressure in real time while filling the tires. Makes it easier when dealing with lots of cars.
I've used plenty of those stick gauges, even some of the better ones and learned if you want 3 very different measurements, get 3 different stick gauges.
There's hundreds if not a thousand dollars of pressure measuring equipment in these cars with warning bells so it ain't the same as the old days and I expect better accuracy than what I saw.

What bugged me was after pumping lots of air into each tire, the car's display readings barely budged.
I would have had less of an issue if the Jaco and the car's measurements disagreed but at least tracked after filling. I wouldn't complain about 1-2 PSI but this discrepancy was over 4 PSI. which is just not right.

 

But were your final readings taken after driving a short distance or was the car still stationary after adjusting the tire pressures? I think you may have to roll it at least around the block to get an updated reading…?

Or…maybe you have some faulty TPMS sensors…?

 

The final readings were taken after several drives and have been consistent during each drive per the car's display readings.
I suppose it could be faulty sensors, although they do respond by showing increased pressure as I drive and warm the tires up.
Most likely it's user error on my part, but like I said I know I pumped lots of air in 4 tires and the car display barely budged.
How do I know I pumped lots of air? The Jaco gauge reading increased by 4 PSI, the Compressor air tank gauge decreased and I heard air enter the tires.

What prompted me to post this thread was Lexus stated on their website that it was necessary to initialize the TPMS system whenever air is added in conjunction with my reading discrepancies.
This made no sense to me but that's what it says here.

https://www.iralexus.com/lexus-tire-...et-danvers-ma/

 

I agree that statement in the manual is confusing, IMO the manual makes confusing statements on other items and other things. On my ES350 when I read that I ignored it. While driving the TPS read near 33psi so decided to check and determine if TPS sensors are reading correctly. On cold tires checked air pressure with my trusty analog gage and added air to cold tires to 35 with measured with my analog gage (discounting the pump gage). Then drove car and in about couple 100 ft checked dash TPS and readings were very close to 35 I est about 1/2 psi different that my analog gage.

I plan on rotating tires myself and will be interesting to see what the TPS do?.

 

That "advice" is simply an effort to get you to spend money on new sensors and lots of trips back to the dealership for more "work". The sensor batteries typically last somewhere between 8-10 years...much longer than tires last. The only time you need to replace sensors is when the batteries die or they otherwise fail. The only time you need reinitialize is if you want to change the "default" or setpoint pressure setting to give a higher or lower normal range of pressures. I've tried initializing according to the 2020 manual but honestly...who can drive 25 mph for 10 to 30 minutes without ever once having to back up (or who wants to every time you change pressures or rotate your tires? Easier to have your tire dealership (Note: I did not say Lexus dealership), take care of it, provided they have the capability. As long as the car can "see" the four TPMS id codes that it expects to see then the system will work. Pump the tires up to 36 psi, confirm with a couple of different gauges, initialize once, then as time goes on, add or subtract air as needed, and forget it. If you have to change a tire (say, for a flat that can't be repaired), then just leave the TPMS installed on the rim, set the new tire pressure to match the other three, and drive on. If the car readout is consistently way off from the gauges then see the dealer with the evidence to show that there's a problem with the system. If you find the "four dashes... --- --- --- ---" on your car display, but no orange light, then something is wrong and needs to be checked out (most likely a bad battery on one or more of the tire sensors).

ps: when discussing this topic, always remember that "registration" and "initialization" are two entirely different things: "Registration" means telling the car's computor what the individual tire sensor ID codes should be while "Initialization" is simply setting the default pressure with which to calculate the alarm level, and the location of each sensor.

pps: right in the manual it says "Always use a tire pressure gauge". In other words, don't rely on the car display as being the last word!!!

 

If you follow Lexus guidelines, you should be measuring your car tire pressure every day. Yea right thanks for the $1000 of extra TPMS in the car.
I noticed in you statement above you say to "Pump the tires up to 36 psi, confirm with a couple of different gauges, initialize once, then as time goes on, add or subtract air as needed, and forget it."
This is suggesting initializing? WHY?

BTW, I'm having problems loading images, they appear in my "edit" window, but more often than not they fail to appear in my post after saving the edit. I am using the "upload" button.

 

I meant the very first time you put new tires on the car OR if you have to replace a tire for a puncture or road damage. After that, no worries. I get my tires seasonally swapped twice a year when the winters go on and then off...otherwise I don't do anything with the initialization. I also do not bother with rotating them...that happens automatically with the seasonal switch.

Just let me add that my 2014 was my first experience with TPMS also...learning it is a process!

Anyway, this thread is getting a little cumbersome so if we need to continue, let's go private message.

 

The TPMS adjusts for the rotation every time in my experience - 2019 model year.

 

Based on my experience with the Gen 6, that's what I thought but need to go back to summer tires on the Gen 7 to confirm. It obviously has a different program for the TPMS so I wasn't certain.

 

Thanks for the URL.

That looks to be something the local dealership composed to provide "simplified", generic guidance attempting to cover all the operating states and procedures of all the implementation variations of Lexus TPMSs. In trying to simplify while still attempting to cover everything, it looks like they may have dropped a bit or two of important qualifying information, especially so in that bolded sentence:
Other dealerships providing TPMS rest guidance qualify the "get filled with air" condition with "if the TPMS light remains on after" qualification. For example, Lexus of Cherry Hill's HOW TO RESET TIRE PRESSURE LIGHT qualifies their reset guidance with:
That simplified, qualified guidance agrees with the more thorough, detailed information found on page 354 of the 2024 LEXUS ES250, ES350 OWNER'S MANUAL USA AND CANADA ONLY in the "When the tire pressure warning light comes on" section:

​​​​​​​

 

I agree that my local dealer's statement regarding the requirement to initialize TPMS after filling the tires dropped critical qualifying language.
That would explain my user manual vs Lexus website confusion.

I am still unsure why adding 4 psi in each tire per my Jaco Gauge and per the Compressor tank gauge did not result in a corresponding increase on the car's display readings. Tomorrow I'll try to measure each tire again with my Jaco gauge and compare against the car's readings. The Jaco gauge matched the car's display readings for all four tires BEFORE I filled air, but not AFTER. It's as though the car's readings simply never updated after filling, although I can see the pressures increase on the car display while I drive as the tires heat up. All four tires currently read 32 PSI per car's display and increase close to 34 psi as I drive.