you'll get a CEL if you dont have the IAT sensor in there, i had mine dangling with i put my intake on (wow that was a long time ago) and it threw me a CEL, then as soon as the grommet/IAT sensor were in it was no problem. I say get the grommet in the hole, then maye put a little bit of silicone around the grommet (not on the sensor) to hold it in place, then once the silicone is dry and set but the IAT in and be all set.