My dashboard warning tells me to check tire pressure no matter how much psi I put to tires.
The TPM on many cars includes the spare. Could be that.
if you've put the correct pressure in there may be a reset button..my MINI has one, once you've got the correct pressure in there gives it a "reference point" for if you've got a slow leak for comparative purposes...check your owners manual to see what should be done here~ mine has a very visible button for this...yours??
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