how can i tell if my map sensor is fooked. as i keep getting the above error on my secs monitor but the car still drives ok

via the secs intruction manual it says ..

"M.A.P sensor input failed"
The M.A.P sensor/wiring has failed.

the error warning has been intermittant..but its been flashing up quite a lot today

any ideas what to check for first please cars a cos 4x4

cheers