Recurring 02 Sensor Problem

[bimmer530]

I have a '95 530i which began having problems last summer. It was running really rough, and turned out only to be the O2 sensors, not a big deal. Last December however, it started doing the same thing again. It was running with no power in limp mode, and the check engine light was on (Lambda Control #2). Took it in and had the O2 sensors replaced again, as well as the ECU temp sensor and plugs. I'm not sure what the most likely suspect is to killing the O2 sensors so quickly, possibly a plugged cat?

When I picked it up the mechanic said it was still under powered, possibly a cylinder misfiring. Since then the check engine light has been on with the same Lambda Control message, and I often notice it jerking while I'm accelerating, and a moderately rough idle at times. Any ideas where I should begin?

[grave77]

seems to me u have a MAF problem ... did u plug it to a diagnostic tool? if you had ( Mixture control ) then I would probably say its the MAF. I didn't have the V8 engine before ... so lets see what others would say about this too.

[bimmer530]

I don't have any diagnostic tools to test the MAF sensor, is there any other way to tell if it's bad?

Do you think this would cause a 1213 (lambda control) code, instead of a 1215 (Air Mass/Volume Sensor)?

[632 Regal]

intake leaks, intake gaskets are notorius on V8s. need to do my own too.

[grave77]

well I'm quite sure of this ... I don't know the codes well ... but I'm trying to tell you from my experience with my car as I had something very similar ... but since ur engine is differant V8... I cant tell. as mentioned below ... air leaks would cause hell of mess ... as I didn't know that my AFM was done before fixing the air leaks form the intake.

[bimmer530]

intake leaks, intake gaskets are notorius on V8s. need to do my own too.

Well, the car's back in limp mode AGAIN... I'm taking it in tomorrow, but I have a funny feeling it will be the O2 sensors again, not even 5 months old. Could the intake problems you mentioned actually cause the sensors to go bad this quickly?

[632 Regal]

The intake leaks can cause the codes to come up, which it did with my car. I cleared the codes with the battery disconnect and then restarted it so the computer would think the leaks are a normal condition and it has ran good since. Never changed my sensors and they have a few miles on them.

[DaCan23]

Not sure how fast a sensor can be killed from exposure to rich mixture or coolant.

This post had a little flyer about O2 sensors being burnt out.

One thing to consider if you have replaced the O2 sensors, is theres a slight chance the O2 Sensor relay could be bad. It's in the Ebox on the pass side. Though figurin out if its bad or not isnt easy, for $12 might as well replace it.

[DaCan23]

Opps heres the post link

http://www.bimmer.info/forum/showthread.php?t=11242&highlight=sensor

[632 Regal]

clear your codes and see if it goes away

[InfernoM3]

I had a problem with my 02 sensor going off too? I changed the 02 sensor, checked for vacuum leaks and replaced a couple hoses? nada, still check engine light. The mechanic told me that 02 sensor is very vague and can mean any error in the fuel mgmt system. I replaced my fuel filter and Fuel pressure regulator. It seems to have fixed the problem. Try those also. These are pretty cheap to replace. filter $15 FPR $55

[bimmer530]

I cleared them and it ran good for a few miles, then the same thing happened again. I dropped it off at the mechanic yesterday. He said the sensors, if bad, would be covered under warranty. The harder part of course will be finding what's causing the dead sensors...

[byurko]

I agree w/ Regal on this one... Same thing just happened w/ my 540 and I took it to my indy (www.stgbmwservice.com), who's excellent, and he diagnosed it as the intake gaskets and the pcv plate.

I ordered the parts up from BMA which cost just under $100... Just haven't had time to do the work!!

Here's the blowup diagram to show where the gaskets are - http://www.realoem.com/bmw/showparts.do?model=HE63&mospid=47410&btnr=11_1498&hg=11&fg=40

Bryan

[632 Regal]

I read here that some of the newer sensors are crappy and arent lasting very long and have a high failure rate. So it is very possible the new sensors have bit the dust and need replacing. I would still look into the intake system leaks because as I said, they are a common occurance.

[bimmer530]

Well guys, got some bad news from the mechanic today. Looks like one other problem that can cause this is a bad motor. He said one of the cylinders had low compression, so he thinks my motor falls into the sulfur problem which plagued the 93-95 V-8's. For the time being, I'm having him replace the sensors again, and I'll take it somewhere to get a second opinion.

Hopefully I like their answer better ;)

[CheapCheap1]

Ummmm...can you tell us how many mileage you have on the clock? And, what brand of the gasoline you've been filling up the most?

Well, I'm a bit worry about the M60 engine under my 540i hood...

[632 Regal]

if you have intake leaks...geez this is like the millionth time I try to explain it.

If you have an intake leak, the computer tries to make up for the additional fuel shortage and make it run right. WITH the additional fuel or whatnot the piston rings get washed ESPECIALLY IF IDLING thus giving you rings that dont seal well. same goes for any other leaks in the system. etc etc... kinda common sence here if you understand engine mechanics.

or you could chalk it up to a bad engine...mines got a couple miles on the Nikasil, ill buy yours as a spare.

[bimmer530]

I had him check for intake leaks, he couldn't find any. Like I said, I'm going to get a second opinion, not run out and buy a new engine.

I've got around 95,000 miles, and have been using primarily mid grade in the two years I've owned the car.

[632 Regal]

the intake gaskets are pretty much tall "o" rings, when warm they seal when cool they leak. The do both as your driving...if you havent replaced them thats the first thing to do if it bothers you. also do the valley pan and PCV plate, all contribute.