my gsr ek is throwing a code. it's a 99 b18c1 in a 98 civic ex. i use a code reader and got code p0135 and 141 both for o2 however my secondary is on the cat which i have unplug cause my pipe is too short for the headers. now what about the primary one, since i don;t see an o2 plug on the stock headers? help would be great.

 

should have one plug coming from under the dash through the floor to your cat and one coming up over your transmission or behind the intake mani going to your header depending on where your bung is at.

get an obd1 p72 and just run the one o2 on the head and use the plug on the engine harness.

 

if i didn't have to pass emissions i would. but i guess i have to look for the o2 on the header now.

 

anyone on bypassing primary o2 for ek swapped gsr since i don't have a 96-99 gsr cat i can't plug primary in to it.

 

You can't bypass a primary o2 sensor. Your ECU needs it to calculate fuel/air. Go to a muffler shop and have them weld an o2 bung to your header somewhere BEFORE the cat.