Hey there. I removed my Evap setup when my B16 was boosted in my 2000 Honda Civic Si. The car is now all back to stock, I've tried a few different O2 sensors with no luck. I was wondering if having the evap setup not hooked up could cause the Primary O2 sensor to fail? I understand how the evap system works, and believe it could possibly make sense? I had a spare stock p2t laying around so I just tossed that in to try rule out the ECU. I've tested the wires from the sensor plug to the ECU, all checks out there. Car runs just dandy once warmed up, but its starting to bother me how it runs like **** until then when its reading off the Primary. And that cel light... we all know the annoyance of that hahaha. If anyones got some input, lets hear it! Thanks!

 

Check for an exhaust leak upstream (e.g. header) or near the primary O2 sensor.