Can anyone tell me what sensor this is please 

 

Right in the middle of that picture is your pre-cat oxygen sensor.

Not sure what the relevance of the title is? Are you looking for the (intake) Manifold Absolute Pressure sensor?

What car are we talking about? Mk1 Fabia 1.2?

Yeah it's the MK 1 fella, the barometric pressure was an error code, I've changed lambda sensor and cam shaft sensor and the cars still got  o power and will only rev to 3000 , would replacement of the pre cat fix my issues do you think.ps many thanks for the speedy reply. 

A few suggestions:

Repost  your question in the Mk1 Fabia section (the Technology Shed is for non-car related stuff, mostly).

Give full details of the car (year, engine code, any relevant recent history), and what error code numbers you've seen, what they've been read by, and what warning lights are on.

Presumably when you say you've changed lambda sensor you mean the post-cat one?  Why did you change that?

Checking the brake servo vacuum hose for cracks and leaks at the junctions of the hard plastic pipe sections is always worth doing.