Pre sense

[Paddington]

Hello friends,  I have a problem with the Pre Sense system on my A3 35 TFSI S line and I would be grateful for any help or advice.  I get the yellow warning light on the dash accompanied by the message "System not operational due to outside conditions, insufficient light"  I've cleaned the windscreen around the front camera (washed the car but it is never really dirty) cleaned the radar panel below to number plate but the fault still persists.  Am I missing a sensor or have I inadvertently messed something up?  I have a code reader but no fault codes are shown.  Many thanks.