Passat hard to start when weather is hot

Hope this question isn’t too simple for this forum. My daughter drives a 2001 VW Passat. Recently, she’s had trouble starting it. She thinks there is a correlation between high temperatures and the starting difficulty. Any advice on what the problem might be? Anybody know a good repair shop in south San Jose? Thanks!

More info, please…

Someone checked the battery and said it was fine. Someone else asked if she’d had the air filter changed and she doesn’t think so. (Dont know what other info would be useful.)

What does ‘hard to start’ mean to your daughter?
Does it crank (arrr, arr, arr) or does it just go click, click, click? Or does it not do anything?

It starts but it takes a long time and a lot of arr-arring. Today it barely started after she got out of the movies about an hour ago, when it was about 75 degrees. So I’m not so sure it’s about the temperature now. An online mechanic suggested it might be a “map senor” or some other sensor.

Here’s what online mechanic said: Sounds like either a faulty map sensor or coolant temperature sensor both are affected by heat and could cause this exact problem even know the check engine light is off the codes are still stored in the computer and have it checked for history of codes and it will tell you the exact cause

Then take it somewhere to have the codes read, silly!
I don’t know where you are, but Autozone (a car parts place) will read the codes for you for free, last I knew.
Otherwise, you (she) will be buying parts that may or may not fix the car.