New Fangled cars and tire pressure monitors.

[GH85Carrera]

OK, I am confused (again) I guess.

I have heard people discussing the inaccuracies of tire pressure monitoring systems. I have no previous first hand experience with them but I am dealing with my wife's 2017 Macan.



This is the sticker on her Macan. It says 36 front and 39 rear as you can see. The display on the dash says it has 30 front and 34 rear. The right front tire showed a low pressure so I added 1 PSI to it to get it to 34. According to my tire pressure gauge it is now at 34 front and 37 rear and that is what is likes to see.

So do I have to just "sneak" up on it with guesses to keep it happy?

Within a month of having the car the front left tire warning came on and according to my gauge it was identical to the other side tire. I mean dead on the same. I had her swing by the dealer and they claim they added two PSI and it was happy. They did not even try to charge anything since we bought the car there.

And as a technical note the tire pressure gauge I use is a dial type gauge labeled a "Accu-Gage" and it reads the same as the other dial gauge I use.

[vash]

my toyota lets me push a button to tell the system where i want to keep the pressure. i simply fill up my tires as desired and push this button..it will then set that pressure as the datum.

my system is dumb and old; so if i get a warning, i still have to go around the car with a pressure gauge to locate the offending tire. including the spare.

[GH85Carrera]

The Macan shows the pressure for each tire individually and will tell which one is off for the magic number.

[javadog]

I don't know what's in your car but in my 08 Boxster I had a system that was absolutely infuriating. It never matched the gauge, it's two screens never agreed with each other and there was no adjustment. While it was under warranty my friendly local dealer replaced all of the sensors, which accomplished exactly nothing.

[widgeon13]

How did we live w/o these stupid options years ago? Mine are a PITA!

[Tobra]

One of the myriad reasons I don't have a lot of interest in new cars.

[RKDinOKC]

Can you use the dash computer to go look at the tires pressure/sizes?

My 90 928GT had a PDK, Tire Pressure Monitor. It would tell you when the tire got to 30 psi when the set pressure was 36. It would error and have problems even when set with the Porsche tool. The only thing that worked reliably was to put the minimum pressure in the tires, drive around the block. Put the maximum pressure in the tires, drive around the block. Then bleed the tires down to the correct pressure. It was 30 drive, 42 drive, bleed to 36. It was the procedure recommended in the Owner's Manual. That routine was setting the sensors in each wheel not the computer part. When set that way it worked wonderfully and never gave an erroneous low pressure warning.

Saved me a couple of times when a tire got down to 30psi and I found a nail in it. 30psi gave me time to make it to a tire shop to get the nail removed and hole plugged.

I would read the owner's manual about the tire pressure monitor to see what it says to do. It may have some procedure to reset the wheel sensors like the 928 did.

[onewhippedpuppy]

My wife’s Nissan Quest gets flaky every time the temp gets under about 40. Normally I add 1-2 psi and it stops, even if the pressure is good.

[pete3799]

My wife's VW Passat doesn't have tire pressure sensors in the tires. It uses the abs sensors for that.

A few months ago she told me there was a light out on the car. I asked which one? She says i don't know the car says there's a light out. I get in, and after fiddling with some buttons on the steering wheel, the dash tells me the right rear backup light is out........sure enough.

[flatbutt]

My Tacos never worked. It flashes continuously. I do it the old fashioned way......I kick the tires.

[sc_rufctr]

Makes you wonder... Why put tech in a car that's not up to snuff?

Like Tobra this is why I like older cars. I truly believe they jumped shark with OBD2.

Not relevant but have you seen the latest line up from Mercedes? Gone are their reliable and robust door strikers.
Replaced with generic rubbish. Even Rolls-Royce & Bentley use these now.

[masraum]

Originally Posted by javadog

I don't know what's in your car but in my 08 Boxster I had a system that was absolutely infuriating. It never matched the gauge, it's two screens never agreed with each other and there was no adjustment. While it was under warranty my friendly local dealer replaced all of the sensors, which accomplished exactly nothing.

Funny, my '08 Boxster is generally within 1psi of what my gauge says.

[ian c2]

My 997 is about 3psi low cold , about 1psi hot .
But it’s consistent , when measure with a long acre gauge .
Out , but consistent .
I can work with that , as it’s good enough to see when they’re upto temp .

The Range Rover that just got wrecked even monitored the spare .
Great idea , after all what’s the point in telling you you’re losing pressure in a tire only to find out your spare is flat !!
Unfortunately , it’s a Range Rover so just added a 25% complication to a system that didn’t work properly

42 psi in all tires , and a 15 minute run sorted it out every time .

I blame firestone and the Ford Explorer ...

[javadog]

Originally Posted by masraum

Funny, my '08 Boxster is generally within 1psi of what my gauge says.

Clearly, your gauge is broken.

[fastfredracing]

Most of them seem to be pretty close when I check them, but I do see one here and there that does not agree with my longacre tire gauge .
I hate them. Adds a bunch of time, expense, and complexity to routine tire/wheel changes .
I spend lots of my days pushing buttons on little plastic devices . I miss the old days .

[T77911S]

a lady at work spent a few hundred on getting hers fixed.

[bob deluke]

My 996 Cab doesn’t have tpms, thank goodness...

[pwd72s]

Part of my wash routine is to check tire pressures with my old blue point pressure gauge. Just don't trust the sensors to be as accurate as it is.

[Bob Kontak]

Originally Posted by fastfredracing

Adds a bunch of time, expense, and complexity to routine tire/wheel changes .

Have you run into the aluminum aftermarket schrader valve caps that corrode onto the sensor's schrader threads? These surely cannot be factory.

I have had to dremel them off with a cut off wheel - after I twisted one right off with a pair of pliers during my learning curve. Half of valve came right with it.

[fastfredracing]

Yes, and also had the core snap off right in the stem. a