I am getting terrible gas mileage in my 90 rex (150 mi or so a tank) and my first idea is changing the o2 sensor, im looking to purchase online, but i cant find out how many the stock si had (my car is at home and i am going to school 3 hrs away and cant check right now), i also dont know how many wires it has (1-4) or if it is heated or not. Any info/places to buy online would be great thinkyou.

 

your car has 1 o2 sensor and it is a 1 wire o2 sensor.

 

thankyou, is there a brand preference or just the least expensive?

 

NGK sells them now, Its called NTK oxygen sensors i believe.
Best i used, made in japan.

Don't use bosche, gave me trouble.

 

are the NTK's splice in or plug and play?