fancy modern car/tire question

[Kali]

how do those automatic tire pressure warning things work? I have a very slow leak - maybe a lb or two every 3 or 4 days. it causes a warning light to come on and that drives me nuts. now even though the car CAME with some goo and a compressor INSTEAD of a spare (not even a donut) the manual warns that it may cause problem with the little sending unit.

now, having lived on dirt roads with plenty of cactus I have used foam for more or less permanent repairs for decades.

is it going to ruin something if I just put a can of foam in there? I am betting the tire repair guys are not even going to be able to find this thing (and with my luck it is probably in the sidewall anyway) it is that slow.