still got an engine light
 

Well I changed the second 02 sensor on the drivers side, after diagnosing it with the OBII code reader, it was po 136. A day later the engine light popped back up, read the code again and it was the same code side 1 bank 2 02 sensor. Now I am not sure what to do don't really want to take it in to a shop...anyone have any ideas or have had this happen to them??
thanks alot for help i am stumped.
also the car has 52,000 KM's it's a 2002, and it has bit of a rough idle..would this be from the 02 sensors or wireing or whatever is worng. I have not changed fuel filter/plugs/pcv since i have had it so i dont think its been done at all.

did you buy Ford O2's or aftermarket?

I work for a parts store so I had 2 choices, a bosch which looked different then the stock 02 and then a standard which looked exactly the same and said ford all over the sensor.

oh, btw I used the sensor that said ford on it.

After you installed the sensor did you clear the trouble code?

i've run into this before the engine light even though it says it is a 02 sensor code doesn't neccessarely mean that the o2 is bad... it could be that the 02 is reading a lean or rich condition.... I had that problem it showed an 02 code and it ended up being a rich condition in the motor cause on of the injectors was bad... do a little more investigating...

Take the main negative off your battery for a few seconds then reattach it and start your car. If the light stays on then it's still throwing a code somewhere.

It takes 10 mins for the Ford EEC to reset itself. If you can go to a shop that can monitor your A/F ratop , i would check that out.

I've left the battery unhooked then cleared the code for a half hour it went away for 2-2.5 days i thought i was clear then it came up again i unhooked the battery again for a while the engine light went away for about a day. I have been running premium all summer last year premium ocassionally, I have heard that the 4.6 2v n/a does not need premium (91-92) so I ran regular but i noticed the car runs better on 91 over 87. But could this be the problem?? I have ran 87 a few times since the light has been on, remains on.
thanks for the help.

I'm assuming it's an aftermarket cat or catted mid pipe.

I'm sure their high flow cats... thing is, they are too high flow so it throws the left/right side bank codes. I had this problem when i got mine. Also your elminating the pre-cats when you do a new mid pipe so this makes it even more of a problem. I've turned mine off with my Xcal unless you get that MIL eliminator??? the tuners are the only way I know to turn them off. I don't know if you can use the elminators(or whatever they are) with cats.

If you have Xcal or a tuner, go into the program and enter "0" under the left/right banks.

If you don't have a tuner, good reason to go buy one

I know if you have an exhaust leak before the 02 sensor, it could throw it off and could cause the mil to come.

The mid-pipe is in fact stock with all remaining cats. I really dont know what it could be...thanks for the help.

Wow, well if you checked the code and it's throwing the Bank codes, than like someone mentioned.. try checking the A/F Ratio... that does make sense.

EDIT: If you dont feel like really trying to fix it, maybe you can find someone with a handheld tuner and just trick computer by turning off the cats all together. That's what I have done

I would still question if you got the right sensor, just because Standard re-boxxed a Ford one does not make it right. what was the stampping # off the Standard one?

as I've posted before, Do NOT use aftermarket electronics on Ford's they just don't match-up wth FoMoCo's specs

i read somewhere else were someone was experiencing the same thing and they found out that some of the ceramic in their cats broke up and plugged up some of the exhaust, causing the same problem as you. if you can get under your car and shake it or knock on it to hear if anything is loose.

that's what I was about to point at. I think you either have:

an exhaust leak after the light off cats (front) and it's freaking your 02s out.

A bad/damaged cat.

A short in the wires that feed the O2 signals to the ECU.

It's all pretty easy to check. You'll need a volt meter to check the wiring and that'd probably be my last step since it a minor PITA to properly complete that test. I'm betting you've got a busticated cat. Buy yourself a catted X or H pipe and slap that bad boy on. It's time for an upgrade anyway. Catted pipes will also sometimes throw codes but at least they're cat efficiency codes and you'll know to ignore them. They also take a while to throw that specific code so it's not usually a frequent issue.

well I was planning on swapping out the mid-pipe, but I am hoping to sell the car and save for the winter then look for a cobra.

my CEL comes on from time to time, I dont even really care anymore....

Just be careful because you'll get used to it being on and then when something is really wrong you won't know it and you'll blow your exhaust or somethin' worse.

you don't leave it on... you disconnect battery and it'll clear. Then next time something trips it you still get the warning.