TPM message AGAIN

[dchou1107]

Last week I took my car to the dealer because the SERV TPM message came up. It was due to low tire pressure and the dealer supposedly made the adjustment. I drove the car home after work and the message appeared. I then took it to a gas station to check on my tire pressure. It was at 33PSI and I decided to pump it up to 40PSI since the max load is 44PSI. The TPM message disappeared for a few days. Now it is back again. THe message that comes on when i flicker the light four times is low tire. Can this be due to a broken sensor. please advise