recently bought a 25 dollar 3a racing air filter from pepboys and had my friend install it since i was busy at the time, however since taking the stock intake out it left one oxygen sensor without a hole so he just stuck it in there and screwed it, works perfect...at first my car idled at about 1.5 rpm's but after a few startups it went back to its normal around .700, however now the "service engine soon" light has came on, I really dont know what caused it or what i could do to fix it, any ideas what could be done or whats wrong since im a "newb" with cars

 

find out the code its throwing out. check the ecu

 

The sensor your refering to is the intake air temp sensor. It needs to be plugged in and should really be in or around the intake air path.

 

i stick mine into the midpipe. it worked great for the last 1 year+, no CEL.