Peugeot 406 odometer does not work

Either a faulty odometer or a faulty sensor on the gearbox.
And though it's not a big job to replace it's a little bit of a pain to get at.
Well for us big hand folks it is!

You dont say what engine , but this applies to SOME models if 1/4 drives good suggestion does not fix .

" £36, ten minutes work, and it's cured!
My 406 2.1DT developed an intermittent speedo fault at about 44000 miles, and I spent over £300 on diagnostic tests, replacement sender unit and a s/h instrument panel. The fault persisted.

I bought a speedo interface box, £36 from the local Peugeot dealer, and fitted it in about 10 minutes. Removal of the glove box by sliding out 2 plastic hinge pins gives access to a plastic cover, behind which lies the speedo interface box. The electrical connection is held by a red clip, which when unplugged, allows the box to be withdrawn. It's a bit fiddly to fit the new box in place because it is located on plastic guides which you can't see, but once clipped in place, and the electrics reconnected - that's it. Problem solved. "

its a petrol 4dr 406,thanks again

its probably the interface that converts the analogue signal to digital