Originally Posted by gerardt20

can the access port stop the light from ever appearing?

Originally Posted by zcast

It is basically a spacer for your O2 sensor on your exhaust. Spacing it further away allows it to pick up "cleaner" air. Per the description: The factory ECU is comparing the readings from a pair of oxygen sensors to measure the effectiveness of the cat. When a high-flow cat is used the exhaust gases are able to pass by the cat at a much faster rate, disrupting the readings. The o2 sensor spacer retracts the second oxygen sensor from the direct flow of gases, restoring the balance that the ECU requires when using a high-flow cat. I am going this route first before I have my tune clear it for me. Reason being is that a cleared CEL from a tune doesn't clear the error from reading codes on the car, and it won't pass emissions. Here in Nevada I believe it is 2 faults = fail. So instead of swapping DPs every year, I will use the spacer and tweak it until it tricks the sensor to reading clean air (hopefully....it's never a sure thing with these things, but have been very successful with VW/Audi with catless DPs). http://www.etektuning.com/42-draft-o2-sensor-spacer/