Wonder if any of you guys know what's going on.

I leave my car parked outside at work (garaged at home). So tonight leaving work, when I start the car to go home, the "low tire pressure" text comes up on the MDI. I check the TPMS and all 4 tires read 30psi (it's usually at 32psi). But the front driver's tire is the one specifically blinking. I figure it was due to the colder weather (~40 degrees all day).

So I drive home anyways. During my drive I noticed all the tires eventually reading 32psi, but the front driver's side tire is still blinking, and somewhat fluctuates between 31-32psi.

I get home, park the car in the garage (the garage is somewhat cold). I check it a few hours later, and it's still giving me "low tire pressure" warning on the MDI, and again points to the same tire. This time though that front driver's tire is at 30, while the others are at 31, 31, 32.

Any clues?

I gave the dealership a call, but no one is available b/c it's approaching closing hours. I'll try calling again in the morning.

 

I have had my tire pressure go down as low as 29psi cold on all 4 and it has never prompt me that it was low. See if you can find out from the manual what the cut-off is for the system to prompt you. if 32 is recommended, how can 30 be considered low?

 

The colder temps can affect pressure readings. I would take readings with an actual tire gauge (I've found the TPMS system displays pressures about 3 PSI lower than when checked with a tire gauge) then fill to the recommended PSI & let sit overnight. Check the pressure again in the morning and if it's more than just a pound or so lower, you may have a slow leak.

I had this same thing happen on my '06 TL. It was a very slow leak, and only after pulling the wheel off and thoroughly checking the tire did I find a small, but long screw. I repaired the leak myself & didn't have a problem with pressure after that.

 

Cold weather affects the actual tire pressure not just the pressure reading on the TPMS display. As a rule of thumb your tire pressure will change a little less than 1psi with every 10 degrees of temperature change, (pressure goes down with cold and up with heat). I've found on our 07 TL that the warning indicator doesn't come up until one of the front tires dips below 29psi but won't shut off again until the pressure comes back up to at least 30psi. The same is true with the rears but at 2psi less, (factory tire pressure is set to 32psi front and 30psi rear). To the OP, I would recommend setting all of your tires at like 35psi just to see if that will reset the low tire indicator. Once the light shuts off you can return your tires to whatever pressure you like them at.

 

Thanks for the suggestions. I'll see what the TPMS says in the morning.

How do you guys pump air into your tires at home?

 

True, it's been a long day... Elevation will also affect pressure as well, losing about .5PSI for every 1000' above sea level. I noticed that on the last road trip to NY, where the PSI was about 3PSI higher than here in the mountains.

The best ~$50 you can spend IMO is on a portable 12V air compressor (along with a patch kit) that you can run off the accessory socket in the car. Griot's garage has a nice one for $60 on their website as well as a full repair kit with 12V compressor.

Then you can avoid using those stupid sav-a-spare tires, should you get a flat or are really unlucky and get two flats!

 

That is very weird. I recently changed my rims and got new TPMS. My tires would not hold pressure at all. The only times the LOW pressure warning came one is when it went below 25 PSI. And it happened on several occasions after I would fill up the tires and it would decrease. I guess in really cold temperature they can expect the tires to go to as low as 25 but anything under that there has to be something wrong. For 30 PSI you shouldn't be getting a low pressure warning. And unless the dealer puts in the air or you have a good tire pressure checker it will be off by 1 or 2 each tire.

 

My TPMS sensors (all 4) read exactly as the tire pressure gauge that I have. The difference of a few pounds especially down to 29 psi should not trigger a warning. Could it be that you have a defective sensor for that wheel only?

 

Just curious do you use the typical plug kit that you find in auto shops? I was thinking about keeping a kit in the trunk but the tire guys said you should never use plugs as they are not reliable. I don't drive 100MPH down the highway.

 

The TPMS low pressure light should kick in when the pressure drops below 25% of recommended pressure. If your recommended pressure is 32lbs, then the low pressure light should kick in around +/- 24lbs (24lbs being 25% of 32lbs).

I would have the stealership check for a defective sensor. These things are sensitive and it does not take much for them to go south, or at least that has been my experience.

I was told that the system needs to be reprogrammed if you are running 19's on the AWD's as the factory recommends that they be run at 37lbs, that way you are not constantly getting the low pressure light

Oh, and I am sure that you already know this, but just in case others do not...... Never use the slime seal to fix a leak when you have TPMS.

 

I'll look into the air compressor. Sounds like a good idea.

No changed this morning. On the MDI front driver's side tire still flashing low tire pressure, ~31psi. All other tires fluctuates 31-32 psi. Mid 30 degrees F this morning, not sure if it matters or not.

I called my local dealership today, and made an appointment to bring the car in tomorrow. We'll see what they say.

 

Just noticed (my bad, sorry) that you have the 6MT w/HPT's. You should be running a factory recommended, 37lbs in the front and 32lbs in the rear. I personally run 40lbs front and 35lbs rear.

Try bumping your fronts to the correct pressure and see what that does. The 25% rule is a +/- thing so at 30lbs it could be triggering your sensor. Just my

 

I agree with TLNV

If that does not work then it probably is a sensor

My pressure gauge reads the same as my TPMS

Remember to always check pressure when tires are cold

 

I just bought this one:

http://www.amazon.com/Viair-00073-He...=pd_sbs_auto_4

I'm very satisfied with the build quality and its performance. It sure beats trying to find one that works at a service station.

 

I bought a kit from Safety Seal who are the original makers of these kits. I've used the patches many times and they are quite good. The patch has lasted as long as the tire did. As long as the hole is not too big and not on the sidewall these patches should work just fine.

 

Update:

Last night at the office, I got a hold of a portable air compressor from one of my staff's spouse. I pumped the front tires (both driver's and passenger's) to 37psi (both fronts "seemed" a little sagging for some reason.) I left the rears at 32psi for now. Sure enough, the low tire pressure message disappeared. Car even drove a little better and sure footed.

This morning I called the dealership and explained what happened, and the service dept said they would have done the exact same thing, to pump air in the fronts. Service guy recommended 35psi all around.

No trip to the dealership needed, so I canceled the appointment (I would have probably gone anyways if they had the ZDX to check out )

I'll definitely look into getting a portable air compressor. The one amazon seems like a good one; is there one by chance that can run 12volt and AC/DC?

 

Like I mentioned in my post... I have 40lbs in the front and 35lbs in the rear and really like the way that the car handles now. I would not put anything less than 37lbs in the fronts as that is the "recommended" pressure from the factory.

Congrats and enjoy!!!!!!!

 

Sounds like the TPMS was programmed correctly to reflect your 19" HPT. 32psi is the rec pressure for the regular tires, and I think they better at 35psi....so like TLNV said I'd probably put >37 up front and >32 rear

 

TLNV...Why do you run higher tire pressures in your HPT beyond 37/32?
Curious...