Hey,
My enginel ight was on so I checked the ECU code, the test that they show you to do on C-Speedracing.com Anyways it came up as 41, which is:
Primary Oxygen Sensor - Heater circuit malfunction

So question is where is he primary O2 sensor? and how to replace it?

 

primary is on the header.. i believe.. to replace.. go to honda.. or find one in the classifieds.. ask for a o2 sensor... costs a lot brand new.. try to find a used one... there should just be a clip.. just clip off the old one.. screw in the new one or am i wrong.. sorry ive been up 36 hours.. mind is kinda dead rite now

 

you may not need a new o2 sensor.

if you do http://www.oxygensensors.com has a good deal for new ones.

 

The primary O2 sensor is located under the car, on the end of the header, just before the catalytic converter. To replace it (if needed) you would need a 20 or 21mm wrench (can't remember which) and probably a can of "release all" or WD40.
first you might went to check the wiring or connector for damage.

 

Don't be cheap!!!!!!!!!
Buy the brand new 02 from dealer because 02 directly related to the fuel supply to the engine, also affect the fuel consumption.

 

check the two black terminals on the connector for tightness, those two black wires are your heater circuit. check their resistance, it should be between 15-40 ohms. i had this same problem, and it turned out my resistance was toast, so I bought a new o2 sensor. now i'm getting awesome mileage

 

a civic o2 sensor is the same as an integra one... FYI