Clio3 1.2 16v at once no longer starts

Hello, I have a problem with my Clio 3 1.2 16V ( 140tkm ) Bj 2008, it was turned off quite normal and worked until then always super 4 days later it did not jump any more. It was already checked in a workshop and said. Fuel comes compression everywhere enough spark plugs work car read out and no error message, but……MKL ( wrench ) is because an error in an airbag I also checked everything and had the glei could it also be due to the immobilizer ? and how can one test something like this ? car turns normally jumps but not have been checked at sensors or whether the timing belt has skipped etc. Now I wanted to check/exchange the crankshaft sensor and camshaft sensor ect but find the camshaft sensor not (or does not have one ? ) Maybe someone knows advice or had the same problem sometimes. Would be grateful for any help. gruß Pietro