i link my iphone via a cable,and during the hot weather tit keeps crashing the carplay app

is it worth trying to update the radio firm ware?

Yes

cheers 

 

Mine does the same, but not always in hot weather, was on a 200 mile trip last week and had to do last 40 miles with car sat nav and the radio (never listen to that)

 

next day and in return trip, no problems 

Not sure about Carplay, but Android Auto certainly seems to have issues more recently, at least with certain phones. I have fairly regular app crashes and restarts when using Waze with my Pixel 4XL that never used to happen until this year - same phone and car, just both have received firmware updates and one has obviously introduced this instability. 

 

Many discussions on the web about it, e.g.

 

https://support.google.com/androidauto/thread/136985712/pixel-6-keeps-disconnecting-with-android-auto-is-there-a-fix?hl=en