My tire sensor needs replaced ,does it just tell pressure ,if so I can use a tire gauge. Does it do more than that? Replacing is expensive.?

You can use a tire gauge? The Angels wept when you typed that. Please do so.

Remote tire pressure sensors are battery operated. It COULD be a simple matter of replacing the battery inside the tire. If one has gone, then it's likely that the rest will fail soon, Get all four done at the same time.

If the tire sensor is out, then it wont tell you anything. Replacing a sensor is different for each car and can range from 60-200$

You can check your tire pressures once a month as needed. I have a piece of black electrical tape over several customers monitor warning light. each of the TPMS sending units in the tires has a none replaceable battery and when they wear out the TPMS units need to be replaced for the light to go out and the system to work. stick with the black tape over the light. By the time you replace all four sending units it will cost you over $100/tire.

It only tells pressure of the tire ,if can live with the warning light on the dash then just check it with the gauge manually.

That's all it does.

It shouldn't be terribly expensive to replace (a dealership might charge an arm and a leg). Call around to some shops and get quotes.