O2(oxygen sensor) code comes back after replacing sensor?

are you sure you got the right one, my Explorer has 4 of them :(

there are actually a few differnt things that can cause a o2 code. It could be as simple as an air filter, also check the wiring harness to the o2 sensor. could be corroded and or broken. May also be another o2 sensor... some vehicles have 2 or 4... left and right bank before and after, make sure you changed the right one. You could also have a bad cat. converter. Also if you don't have the equipment to reset the codes drive cycles will restet codes if the proper repairs were made. With new inspection procedures her in NY and in many other states it is not recomended to reset codes as drive cycles can be more than 100 miles in some cases...

On this stuff you can not just replace parts. You need to make sure the other sensors and controls are working right. Without knowing the type of car you drive hard to help you.Is the wiring from the sensor to the computer good . It could be the injector dripping and the computer can not lean out the mixture enough. This cause a false O2 sensor code. Could be lots of other stuff to. Fuel pressure to high or low , map or maf sensor out of cal. Tough to give you an answer with so little info

Agree with Vonnie C. It's situations like this that expose why you get what you pay for with a "free" code reading at the parts store. More often than not an O2 sensor code does not mean the sensor has to be replaced. There is a long list of tests that have to be run to determine what caused the code to be triggered. Depending on the make/model/year of vehicle there coudl be dozens of different tests and checks required to determine the cause. Your issue requires a real mechanic with real diagnostic tools and expertise. That's why they make the big bucks.

Sounds like you something else may be triggering the light. Vaccuum leaks cause a lean O2 code. So do bad fuel pumps and dirty MAF sensors. Whereas a bad fuel pressure regulator can cause a rich O2 code, but worn spark plugs or a missfire due to bad wires can as well. Parts stores read trouble codes for free because they want to sell you parts, but you need some good ole fashion diagnosis on this one.

Is it on a chevy truck? One thing you want to watch out for, is if you have an exhaust leak, ahead of the o2 sensor. That will cause the light to come on again. depending on what kind of vehicle it is. could be the coolant temperature sensor.

i own a repair shop,,and after you replace the sensor you have to erase the trouble code from it,,or it will come back every time,,and if it has more than one sensor it may need more than one replaced on it,most cars now have to,,an updraft,and a down draft on them,,good luck,but remember ,it has to be erased from it,,good luck with it i hope this help,s.

i think some cars have more than 1 oxygen sensor. maybe there is another one that is bad?