Mass Problem

Hello.

I had posted for a week that I have read out my error memory and found fault.It was probably due to the missing mass connection.Can this be due to the timing belt change ? Do I have to screw a cable?
After I had temporarily laid a new ground line, the control unit found only one error message: No signal to the air temperature transmitter.

How can I check if the pump for intake air temperature is defective?





Greetings Yener