Hello and Welcome -
My name is ***** ***** Im happy to help / advise -
The Map sensor is usually a very reliable item - but can be ruined by ingress of fuel or carbon - which will finish them prematurely -that is your most likely fault.... It could be and over voltage fault - though I doubt it - but you could check the wiring... It should have a feed of either 5v or 12v... Im not 100% sure but if you see a reading close to each of those respectively, thats right --- If its well over 12 ..or say 9 .. then you have an electrical fault - that needs to be traced down.
If the electrics are ok - then start by checking for fuel in the pipe that feeds the Map sensor ... If thats the issue - clean the pipe out and re route it so that it goes up and over to the map sensor - this stops that happening - unless its really bad in which case you would have to trace why...
If its not that - then its usually carbon - the stage then is to remove the Egr valve and check / clean that inc the inlet manifold - what happens is flakes go up the pipe and ruin the sensor - One or the other as above will be your cause...so you will find it working through as above.
Just one point - I assume you are buying / fitting new -not second hand... and a quality product -not a cheap type.. Such ones do fail .. Its best to always go for OE with these sensors.. they are under a fair amount of working stress.
Im very pleased to have helped you - Do let me know if you need anything more --*** Meanwhile - - >>>> Please do click on the "OK/ Excellent ratings" for me - Thank you in advance for that...You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..Kind Rgds, MIKE.
Many thanks Mike - will relay all that to the guy who fixes my car when it goes in again in a few days time