0.3-0.7 vdc or 300-700 milli volts DC = same thing.

it should scan quickly from one to the other if its working - BUT if its just very rich - it will read just over 1 volt (1000 mv) all the time, which was how we come to find it was the MAP sensor ; i'd already changed my lambda as it tested as faulty - but then so did the new one as soon as it was fitted - things started pointing to that it wasnt the lambda after all