http://www.gendan.co.uk/viewproduct.php?product=STNISO
if you download the free software. Unfortunately, my 2000 Zafira was not
compatible. 2001 and younger petrol cars should all be OBD2 compatible.
If you have an older car like mine, the fault code is flashed out on the
engine light when pins 4 and 6 are shorted together, on the OBD2 connector
directly under the handbrake area, and the ignition is on.
To prove it worked, I disconnected the EGR and got 1405 flashed out which is
'EGR failure'!!
In summary, the early Zafiras are not fully OBD2 compatible, but give out
OBD2 codes. Go here to get manufacturer specific info on any code flashed:
http://www.gendan.co.uk/codebank/
HTHs.