406 Auto

I live in Melbourne, Australia andhave had problems with my 406 with the
gears very occasionally slipping and sometimes clunking severely on the
downshift. The gears occassionally also get struck in any gear. I have taken
to Peugeot dealers and Peugeot accredited auto transmission specialist
however the problem still remains. After 100,000km the gearbox finally
blewup. I replaced the gearbox with a secondhand one that had only done
30000km. I have exactly the same problems again. I have replaced the
gearbox computer - no good The faults listed in the gearbox include, engine
speed check, trottle potentiometer and engine torque signal. There are no
faults listed in the engine computer. No one seems to know what the problem
is.

 

I had very similar symptoms on a Mitsubishi Galant auto I used to own, after
a full stripdown and re-build of the autobox, it turned out two of the
drivebands where worn out...
But you have replaced the gearbox, and gearbox computer, so it must be
something to do with either the engine management system, or an engine speed
sensor of some type.. but I would be guessing...

 

Probably a silly question but have you tried switching to sports mode?
In this increasingly complex world work-arounds - such as changing
programs when one becomes 'iffy' - often provide a solution - if not a
cure.