A friend of mine needs a new ECU in his 99 EX manual, which from what I've read is OBD2B. Would an ECU from another 99-00 EX work fine without any problems?

I know in Integra's like mine you can't swap OBD2B ECU's because of the immobilizer, so I wasn't sure if the Civic was different since they don't have that.

 

Yes you will need another 99-00 EX "manual" ecu for it to run fine. Make sure the code says P2P and that it's OBD2b ecu.

Refer to this link to see whether it's OBD2a or OBD2b

http://www.hondata.com/techecuid.html

 

Great, thanks.