OBDI code 1221
 

Okay, most of you guys know my car, '92 325i/M50 (OBD I). I'll try and make this short . . engine threw a CEL about 10 days ago, fault code 1221, which is the O2 sensor. While waiting for the sensor to come in the mail, the car drove crappy- hesitation under acceleration, loss of power, rough idle, greyish exhaust smoke, and in once instance, the car died.

Once I installed the new O2 sensor, the CEL remained lit, and goes on and off intermittently. The car ran rough for a day or two, but now it's stable and idles well. No more loss of power. There's still some grey smoke, but not often. The car is now responsive but the CEL is still on. I checked the MAF, the ICV, and the throttle position sensor, and they're all working fine. The O2 heater and relay tested fine. I've read that it takes a couple of cycles before the CEL shuts off and the fault is cleared, but this should have happened by now. The only thing I can think of is if the new sensor is defective, or maybe I fouled the sensor when I installed it, but I was very careful about that. Anyone have any ideas? I'm at my wit's end here :angry

try disconnecting battery for 10 mins, reconnect & do a minor roadtrip - say 50 miles roundtrip at highway speeds. That cycling includes getting up to normal running temps - winter isn't actually friendly to our engines reaching normal op. temps.

Yea, I'd been running the car on the highway the past few days, taking it through its paces, but it hasn't helped. But I just tried disconnecting the battery for about 15min after your post. Just got back from some more driving, now the CEL is only on half the time :dunno

if it turns off and turns back on you have a problem, see if it stayed on then it would probably be that you just need to clear it. maybe you didnt connect the wires properly and they keep disconnecting or something else, run the fault code reader again, if its the same reader take a second look at the 02 sensor

The wires are idiot-proof; it's a twist-lock connection. At any rate, the fault code has now changed to 1222, which is means the sensor detects an overly lean or rich mixture. I've gone though pretty much every vacuum hose behind the MAF sensor for leaks or cracks, and cleaned the throttle body/plate. Funny thing is that right now the car is running the best it's ever run since I've owned it. I'm thinking either the new sensor is defective, or I may have fouled it. I guess I'll know when I change it again . . .

Before jumping the gun, this time of year will contribute to that "to rich" because of weather (that's why I suggested the highway run) According to my buddy Doug at BMW he says "being winter it might need a longer run on the highway like an hour plus at highway speed and normal op temp. Cold start up gave it a coating of excess fuel - he says they have to go through a couple of cycles - air filter also makes a diff - low restriction K&Ns and CAIs can add to the cycling time increase.

Hmmm . . maybe I'll go for a nice run to South Jersey this weekend- Atlantic City?? :D I just hope I'm not damaging the cats before this problem is resolved :(

Problem still unresolved. Anyone good at O2 sensor readings? The sensor is definitely working, and it maintains a mean average of .426v when at warm idle. It fluctuates slightly, but not much. But the engine does shake for a minute or so just before reaching operating temp, and the readings during this time shoot up to .8v and .9v. Once the shaking stops, it drops back down to .426v. At this point, the CEL lights up, but the idle is rock steady. Which tells me that the DME has compensated for something wrong. Bentley says it should be somewhere between .2v (lean) and .8v (rich) at idle, so being in the middle should be about right?

EDIT: never mind, I found my answer. According to everything I've been reading, the voltage should fluctuate rapidly and across a wide spectrum, from .2v to .8v, and not remain steady. If the reading never goes over .6v, then the sensor is damaged or dead. And the fact that the CEL comes on and the idle smooths out means that the engine management system has gone into open loop and will run rich to compensate for the lack of O2 sensor input. So it seems I probably fouled the new sensor when I installed it :( :doh

Good to hear, at least you know whats wrong now. When are you getting a new sensor?

^^^Ha. Thought I\'d get it at the local stealership, but when I called, they quoted me at $179. To which I replied "that\'s well over 300% markup. Do you guys even know what year it is?!"

So I\'m buying it from AutoHaus, getting it sent UPS Red Saturday delivery. Even with the expensive next day shipping, it\'ll only be about 90 bucks. Tomorrow\'s temps will be around 50deg, so it\'ll be a good day to do this. I just hope that\'s all it is, nothing\'s worse than mystery problems of this type.

Update: things get worse. I found the O2 sensor at Pep Boys, so I installed it this morning. But when I pulled the old one out, it was wet, and there was a lot of moisture in the exhaust pipe. I don\'t know what this means. The new sensor didn\'t solve the problem, and is probably fucked again. Then I drive to work. I get in the parking lot, shut the car off, and boom- the coolant expansion tank blew up. So now, I\'m sitting here waiting for a tow back to the house. I FUCKING HATE THIS CAR.

Dudesky, sorry to hear about your troubles. Didn\'t you recently replace that radiator? Don\'t know what to tell you, because you\'re "Mr DIY" King in this forum - so I know how detail oriented you are. Sounds like an inferior part somewhere along the way - not your work or efforts. Hope you get it resolved without alot of hassles or $$$

The radiator was replaced in May but there\'s no problem with it, the expansion tank is what blew. That was just replaced in Sept. But I\'m pretty sure all these things are related somehow. Just wish I knew WTF is wrong. I hate this feeling; I got all kinds of things going thru my head, like maybe the coolant is seeping into the combustion chamber, but there\'s no sign of coolant in the oil, nor any oil in the coolant. But that doesn\'t mean it isn\'t leaking into the cylinders. I just don\'t understand why there\'s heavy moisture pre-cat by the exhaust manifold, and fouling the O2 sensor.

Anyhow, UPS Saturday delivery should bring me a new expansion tank, engine temp sender, coolant temp sensor, air intake sensor, and I\'ll run over to Pep boys for a new O2 sensor. I\'ll pull out the spark plugs to see what they look like. But this is the last of it- if I can\'t resolve this over the weekend, I\'m not spending any more money on this POS. Maybe I\'ll get a beater E30 till I graduate and change careers next year. In the meantime, I\'m gonna go get drunk :beer

Final update . . Well, I guess this is it. I put in the new expansion tank, and sensors, but nothing has changed. Then I pulled the spark plugs out, and every one of them looked like this:

http://files.unitedbimmer.com/ub.c/Dudesky/oil_plug.jpg

Major oil fouling. The cylinders were even worse. Just looking into the spark plug hole, I could see the oil glistening on the top of the pistons. This poor Bimmer is fucked, could be worn piston rings, valve stem guides or seals. And there ain\'t no way I\'m gonna tear the engine apart and rebuild it, just way too much already, and neither do I have the time on my hands.

It\'s not a definite decision yet, but I\'m pretty sure you\'ll all be seeing parts from my car in the classifieds section :cry

Oh wow I\'m sorry to hear :( How many miles are on it? I actually have trouble seeing that :conf