Do you have a LS or GSR swap? If they swapped over a ecu from a 2000 integra then it should be OBDIIB. To find out what ecu you have, read the number on the ecu itself and refer to this:
http://www.hondata.com/techecuid.html

However, I believe you don't have an OBDIIB ecu since the 2000-2001 model came equipped with the immobilzer unit. I believe if you use that engine with that ecu, you'll need a matching immobilizer control unit in the steering column along with matching key to start it. You might have an OBDIIA (1996-1999).

Did they do a full engine harness swap? Not exactly sure why the sensor isn't connecting. One reason I think is because your integra is a 94 which is OBDI and the swap is OBDII, maybe you need an OBDII--->OBDI harness. :dunno: