First thing to check under the rear of the car is the waste gate arm, it’s held in place by a tiny E clip and these can rust and fall off meaning no boost will be allowed at this point. Be careful as the exhaust is very hot and you need a clip to be able to fix it. *safety note potential hazard item* Secondly, if the car is standard get the car diagnostics checked. It could be the cycle valve, check the hoses to it and if it needs to be changed then check the boost pressure sensor (look at the reading to determine if boost is produced or not). In the case of remapped cars it could have gone into safe mode (a get you home mode which uses much less power). *safety note potential hazard item*
