306 Td Oil Level Gauge

[Rob Turbo 3]

The oil level gauge on my 306 TD doesn't seem to work properly, when the ignition is turned on the needle goes from empty to full, back to empty, up to about half way, then back to empty, all fairly quickly, then slowly riseses a little bit. It does this even with no oil in at all (I tried it when I was changing the oil a while ago!) so I'm guessing it's the sensor that's broke or clogged up or something, but is it likely to be fixable? They are £62.11 from pug and I don't want the gauge to work that much!