Land Rover Repair: 01 rr hse P0452 for over two years now, purge valve, smoke test

Question
I have had this code continuosly for ovr two years. I have had the fuel pump,
ecu, gas cap and purge valve all replaced and I still cant get rid of it. It has been
to the dealer over 6 times and they cant seem to fix it. DEQ wont pass it cause
the light is on. I can clear it but as soon as it is restarted it shows code is
already pending before any systems are started...HELP!!

Answer
There is a valve in the fuel filler neck that can stick.  It's a common problem in Discovery II of that year and we see it sometimes in Range Rovers.  If those other possibilities are truly eliminated I'd look at that and also do a smoke test to see if there are leaks in unexpected places.  We get a fair number of those persistent failures here at Robison Service and thay can be tough to sort out.