Where is the fuel tank sender on a Peugeot 309

In the fuel tank. You need to drop the tank and pull the fuel inlet and fuel gauge sensor assembly.

hmm,309...cant recall off hand but lift the rear seat and boot carpet.with any luck theres an inspection cover u can remove to get to it.failing that its off with the tank...

l think it is very similar to the 205. Yes, look under the rear seat, there will be NO carpet hiding a big plastic cover. Easily pried off with a screwdriver,
But, l had to fabricate a special spanner to unscrew the plate in the petrol tank. l used a steel pipe, about 2'' diameter, and 12 inches long. l cut one end to provide two ''little fingers'' about 1/4'' long. These fingers could twist the metal plate counterclockwise and open.

Gearhead is correct it is locate inside the fuel tank.

under the rear seat there should be an inspection plate sender is usually under there