Reverse sensors

Most of these kits come with 4 sensors,but can they be used with only 2 sensors plugged in.

In a past life I used to install such things and the ones we used were either 2 or 4 sensor but they were different control units for each type. Can't for the life of me remember what brand they were though.

Cheers mate,
Ive bought a 4 sensor one off the bay but was wondering if ok to use just 2 sensors.Might just wire it up and see.Was just worried as if i put the 4 in the rear bumper the middle 2 would be uner the spare wheel and in the recess where the number plate is.

I can't see an issue with putting 2 in the plate recess assuming they are able to be mounted securely and angled to accommodate the blind spot, are they surface mounted or flush mount?
Most of these operate using a cone and triangulation of the intersection points, the more sensors the nearer the overlaps the finer the sensitivity to objects, so if you can, use all 4.

Thanks this is the kit ebay item370963950468 ( only £12 but mates been using one for 3 yrs with no issue, not jimny) .The sensors flush fit into the bumper but i was worried the spare wheel above would up set the sensors in the recess.

The reversing sensors are designed to give a wide angle in the horizontal plane but a narrow angle in the vertical plane, otherwise the signal would bounce back off the ground all the time - they should be marked 'top'. They are a fairly standard sensor, I have a datasheet somewhere, I'll look it out.
I also replied on the other thread, if you don't fit the extra sensors then you shouldn't have a problem because the controller won't see a return signal on the 'spare' channels, it depends on how it interpolates the data.