I have a question and hopefully someone can help me out. I just put on an 02 housing on my evo 9, and later that week i had to get an inspection. I failed it and the codes that it threw out was that the 02 sensor circuit had no activity detected and low voltage. I am running higher boost on my stock turbo. It is still running great, but is this a problem and how do i fix it?

(the service engine light came on after i put the 02 housing on but i restarted the battery and it went away)

 

even if you restart the battery the code will be saved on the ecu... sorry to hear that

 

I dont understand what you are asking...disconnecting the battery cancels the code temporarily. Assuming you still have an issue once the ecu goes through its system of checks the cel will return. You must have damages the sensor or something during the installation. Are you sure the connector is fully connected?

 

Recheck the wires and make sure thes not a short or a burnt wire. This will ground the voltage to zero.