can you test Lambda sensors ?

[benters]

My renault megane is playing up, and been a carb and dizzy man this electronice sensor stuff is all new ! i understand the principles of what the sensors do, but as the car is running poorly and this morning cut out altogether i wondered how you go about checking if the sensors are working properly. I dont have home diagnostics so is there any other way to avoid just changing sensors and hoping to get lucky, or is it a trip to the dealer time do you reckon ?

[benters]

thanks guys. . . a pal of mine has the equipment you refer too so its a trip over to him when the crate re-starts. . .symptons are it hates to re-start once its been running. . .