P0236 - Boost/Map Sensor

Hello! This is my first post so hopefully it’s in the correct forum

I’ve recently purchased a Mk1 Fabia Vrs which has been sitting for 1-2 Months outside my home. It’s a project car and awaiting new parts.

A problem which has developed is a eml fault code P0236, which is Turbocharger Boost Sensor A Circuit Range/Performance.

I’ve had an oem plug/connector re-wired in, as the wires had damage to them (previous owner done a poor job connecting a new plug. I’ve had it professionally done with solder & headshrinks.

The sensor itself is fairly clean, it’s a 4 bar. I’ve purchased a new one (same part number) which is a genuine bosch sensor. Gave that a go, and still no luck.

Once I clear the code, and start the car it will boost. As soon as I turn it off and try again, the light is back on and no boost. 

Can anyone please give me some advice? The problem has come to surface after it’s been sitting for a while. I presume there would’ve been some warning signs if there was any turbo issues (1756) & the car’s not been driven to develop any boost leaks (someone please correct me if I’m wrong. 
 

One more question, will the new sensor have to be mapped in? It’s the exact same part number. I’ve heard some say yes and some say no. Thanks!