I borrowed an OBD2 scan tool to try to diagnose a fault with my 306, but although the connector is the right shape, the one on the car seems to have a little lug which prevents the connector on the tool engaging. What's going on? I though the connector was standard. Am I being a muppet?

What year?

I thought they were the same. Remember there is OBD1 aswell.

I think the cut off year was around 2000. Maybe 2002.

Peugeot group left becoming OBDII compliant until the last minute 2003 onwards.

Ah, Ok, thank you. It's a 2000MY. I was just surprised that the connector was almost, but not quite, the same as the OBD2 one.

Mine is a early 2001 and OBD2 functions fine with it. Not many live variables available but it works fine.