It is part of the fuel sender unit, which is on top of the fuel tank, under the rear seat on the left (USA driver's) side. Unless there is an aftermarket solution, the pressure sensor is not available as a separate part - you have to but the entire sender unit. And then you may have problems disconnecting its in-tank fuel lines from the the pump unit (on the right side) because the plastics get brittle and break. So often times, you send up having to replace both the sender and pump units.

 

Yeah I read that too may have to replace that will be removing seat and checking myself to make sure if I can take it off. I actually found the ftp sensor for sale by itself like it is something that can just connect alone and not need the whole sending unit hopefully

 

Wanting to replace the fuel tank pressure sensor to get p0452 (low input)code off. Already have replaced evap emission sensor as it told me to in a check.
Upon looking under seat i indeed found out Fuel Tank Pressure Sensor is part of the whole sending unit so I will try to replace my sending unit.

Any tips or what too look out for would b great also had a few question about the moisture in seen on the pics, no visible leak of liquid at all more oil-ish like View attachment 2664637

 

Sometimes you get fuel leaks around the seals and they can collect road grime. Also, oil leaking from the engine or transmission can makes it way onto the top of the fuel tank dues to air currents flowing under the car.

As I said earlier, the pressure sensor is not a separately available part, at least not from MBZ.