a guy from my work bought a 93 civic with a 97 b18b swap. he said the idle was surging and it had a cel, so i checked to see what codes he was pulling. it was 12 (egr) and 41(primary 02).i have never owned a obd2 car so i dont know much about them but when i look under the car and there is only one 02 sensor. maybe im wrong but i thought obd2 cars use 2 sensors. but i figured the car would run horrible with a missing 02. it runs pretty good though, just a surging idle from the bad egr valve im guessing. what you guys thinking?