thanks for the input peterb
however as I stated in my original post pre 2001 petrol Peugeot's use a proprietary none standard protocol and the only thing that will read them is a lexia3 diagnostic uint.
Mine is 1998
Citroen uses the same protocol so the same lexia3 unit reads those as well.
You will note in that thread you link they are talking about the diesel models their compatibility was totally different.
The diagnostic port is exactly the same as OBDII but ELM327 readers will not work (I know this for a fact because I have an ELM327 and it does not work. and it's not a fault with my reader as it works fine on my next door neighbours 2004 nissan)
2001 and later the laws changed and all vehicles manufactured for the EU market had to be OBDII compliant so any after 2001 will read just fine with an elm327.