Glisse

The indirect (ABS sensor) based system works on a differential basis, ie one tyre on one axle is rotating at a different rate than the others. If all 4 tyres happened to lose the same amount of pressure at the same time, the system won't trigger.

Quite right, and even worse is the OP seems to be using US market maximum pressures for the local market all-season tyres: 245/40R18 97H on an A5 cabriolet. That will be really horrible having 38psi in the front and 41psi in the rear. This is the problem with the NHTSA holding onto that flawed decision for the last few decades - the maximum pressure depends on what tyres you are actually using. Cover up the door sticker, and use the manual!!

The correct pressures for the OP's 255/35R19 96Y Continentals, according to Audi USA and what is likely in his user manual, is 35 psi FRONT, and 32 psi REAR for a normal load, ie without a football team in the trunk. Having 41 psi in the rears is probably causing traction issues which is affecting the ABS sensors.

WM711

Thats about what the pressures were when the false pressure warning was triggered the first time. traction issues? Its an A5

WM711

My question distilled down is, is anyone aware of a glitch in the Hardware/Software systems would trigger a low pressure warning message, twice, at different pressures, for all 4 tires at the same time? It seems to happens after about 20 miles of highway driving. Ive driven about 50 miles since the last event, short trips, no problems. I do appreciate the help and responses.

uberwgn

Bill, are the tires new? What brand are they?

Also, heed what Glisse mentions about getting your NORMAL load inflation values from the car's Owner's Manual.

Dan99

I have not had any issues with the low pressure warning, but I also have an older version of the MMI. Try clearing the codes as mentioned above to get a fresh start.

The tire pressure warning is to alert you if the pressure drops below an expected level. It's designed to detect one tire going flat, but will also trigger if one or more tires is underinflated. That is why you need to reset the MMI pressures when everything is cold. I would let the car sit overnight, not just a few hours. The heat from the engine will keep the front tires warmer for hours.

1) Get the tires cold (overnight), 2) check/set pressures in all 4 tires before moving the car, 3) store the new values in the MMI, 4) Drive. The heat will go up as you drive and should not trigger any alerts. It's only when the pressure drops unevenly or is significantly below the stored settings. However, as Glisse pointed out, the tpms in your car is indirect and works by monitoring rotational speeds of the wheels instead of directly reading tire pressure, but this should not matter if you set the pressures when cold, then reset the MMI. I had the same type of system in previous S4s and they worked fine as long as I followed the steps above.

If you still have trouble with this, I would take it to the dealer and let them figure it out.

WM711

Thanks for the responses, everyone.

Tires are 255/35/19 Continental Pro Contact AO with about 6000 miles on them. This morning adjusted pressure to 36 front/33 rear, as suggested for A5 Cab w 2.0.

The closest Audi dealer is a couple hours away. I do have a VW dealer about an hour away. I really hate not having a spare...

This car has been flawless. Premium Plus Mythos Black/Okapi Brown. It's my first Audi in a long time. Started out with an 85 Coupe that I put nearly 300,000 miles on, my previous was a 200 Avant, Pearl white 5 speed. Wish I still had it.

I certainly appreciate the input-
Bill Woods
Paducah, KY

Dan99

These pressures seem backwards to me. The front of the car is heavier which means the front tires will need more air to support the weight. I would expect 41/38 front/rear, instead of 38/41 front/rear. Also, I could not find any A5 Cab pressure charts that listed 41 in the front or rear. What model year and engine do you have? For example, look at the charts in this post:

https://www.audiworld.com/forums/aud.../#post25431008

Having the rear tires overinflated, relative to the front, could mess with the indirect tpms mechanism which is dependent on wheel rotation speeds. You might want to review this thread on tire pressures if the problems continue:

https://www.audiworld.com/forums/aud...tires-2989549/

uberwgn

I am using this VIN to get into the Owner's Manual lookup system: WAU2AGF58NN003155 (2022 A5 cab)

Owner's Manual look up system: https://ownersmanual.audiusa.com/

See page 261 of the manual.

WM711

I took a picture of page 261.

Dan99

This chart is from your p261 (I removed everything but the Cabriolet pressures). I don't see 35/35 or 32/32 anywhere, but I do see the 38/41 for a Maximum Load. Do you typically have people in the back seat? If not, you should use the pressures under the Normal Load columns.

The Normal Load options I see for an A5 Cab with 19" wheels is either 35/32, 36/33 (front/rear), depending on the specific tire.