The infamous ELM327 OBDII device came without any paper, just a crappy CD with no document related to the device (only some software and drivers thrown on the CD almost randomly).
I tried the following codes without being able to pair it with my HTC Desire HD:
0000, ..., 9999
1234, 2345, 3456, 4567, 5678, 6789, 7890
What other PINs should I try?