replaced o2 sensor.. worked.. now i have same error again!

[Natopotato]

after getting 1221 error.. i replaced my o2 sensor and my mpg went from 14-15 around town regular driving up to 18-19MPG around town..

i was soo happy...

less then 1 week later i now have 1221 error code and im getting 13-14MPG!!!!!



AAAAGGGGGGGGgg

wtf

what do u guyz think...



my wallet cant take this much longer
i might have to stop or somthing

 

[Willis]

Nanopotato,

If the error has reappeared, check to see that the sensor hasn't come loose. That would be the easiest solution. If nothing appears to be loose than it could be (unlikely) a faulty sensor or it was somehow damaged during shipping/installation.

I installed mine yesterday and I know how hard it is to install. I drove up on some ramps, squeezed underneath, and one-armed the new one in place. I had to destroy the old one to get it out, cutting the wires to get a closed-end wrench on.

Let me know what you find.

 

[andreyiv]

I usually get 14 mpg city driving but the only code I get is 1444 (everything ok). I know I have to replace the oxygen sensor because BMW recommends doing it every 100k miles and the car has 96.5k miles on it right now. Now here comes the dilema, which one should I replace? The 325 has two sensors, right? Which one should I replace, the one for cylinders 1-3 or 4-6, or both? BTW, the car is a 325i, 1995 (pre 09/95). Thanks in advance.

 

[manuel]

i replaced both of mine, its a big bastard to get under there. "kill 2 birds with one stone"

 

[m50POWER]

I usually get 14 mpg city driving but the only code I get is 1444 (everything ok). I know I have to replace the oxygen sensor because BMW recommends doing it every 100k miles and the car has 96.5k miles on it right now. Now here comes the dilema, which one should I replace? The 325 has two sensors, right? Which one should I replace, the one for cylinders 1-3 or 4-6, or both? BTW, the car is a 325i, 1995 (pre 09/95). Thanks in advance.

Since your car is 1995, it should be OBD 1 and have only one O2 sensor before the cat-converter.

 

[frolf]

umm, i thought OBD II's have 4 02 sensors?

 

[andreyiv]

Since your car is 1995, it should be OBD 1 and have only one O2 sensor before the cat-converter.

That's great news for me, I don't have to spend 200 bucks, just 100 . So you are sure it only has one O2 sensor? I just wouldn't want to buy one and while replacing it notice there is another one. BTW You said it's located right before the cat back, so I guess I'd have to get my car up in the air, or is there another way? That's a lot for the help.

 

[flyinH]

jacking up the car or using ramps is the easiest way besides a lift.pre '95 should only have one O2 sensor.using an O2 removal tool helps alot as well.

 

[andreyiv]

flyinH, I finally got the sensor and tried to change it but forgot about that tool and couldn't get to the sensor at all. How hard was with the tool? Did you have to remove anything to get to it? Or should I just go to a mechanic at let him do all the work for me? I just don't feel like jacking up the car again and getting nowhere for the second time. Thanks in advance.

 

[BigEarl325is]

Natopotato, you could have a leak in your fuel injector o-rings. It's rare but it can happen. Pull off your fuel rail (be the hell careful) and inspect the o-rings on the fuel injectors, there should be two per injector (I think) if they're dry and cracking, replace em. What happens is when the intake valves open the air is read that's fed through the MAF so the engine knows how much fuel to put in. Then once the exhaust reaches the O2 sensor he says "hey wait a minute, there's more air down here than there should be" so your computer says, "uh oh, bad o2 sensor" which in this case is not true because it's brand new. So do me a favor and check those fuel injector o-rings, they may be leaking extra air into your cylinders that your MAF doesn't know about.

 

[frolf]

wow, BigEarl you own at bmw's.

 

[BigEarl325is]

Thanks frolf but as I explained to somebody earlier, I think andreyiv, I'm just a parrot. I'm passionate about BMWs so I remember what I hear, but I don't find this stuff out myself. I just learn from the master, Don Fields aka Mr. M Car. His shop deals almost strictly with BMWs ///M division and I've become very good friends with him. Most times when I see someone on here has a problem, if I don't know about it, I'll ask him the next day and relay the message to you guys. So I'll tell Don that frolf says "you own at BMW's"

by the way, manuel, frolf was right, OBD-II cars do have 4 O2 sensors. Thing is, some go bad before the others. The initial O2 sensors (the ones before the cat) will go bad just like any other O2 sensor. However, the back two O2 sensors won't go bad NEARLY as quickly. The air traveling across those O2 sensors has already been treated by the catalytic converters and is typically cooler and less harsh on the O2 sensor itself. So you should be good manuel, but I'm just letting you know.

 

[Natopotato]

thanks guyz for all the advise awile back based on some other advise i replaced my leaking valve cover gasket and installed a new o2 sensor and im all set now.... 18-19mpg city.... much better!!

thanks