Service engine soon light came on and went off but back on again
 

Hello everyone, I tried to search for a thread for this problem but was unable to find one, doesn't mean there isn't one but my tech abilities or not to good. So about a month ago the Service engine soon light came on for a couple of days and then went off. It's back on as of today and I was wondering if there was a common problem that causes this and if anyone else has experienced this. We have a 2006 3.0i with 100,000 miles. Any and all suggestions would be greatly appreciated.

Thanks

Get code(s) history read...many autoparts joints, eg Autozone, Advanced Auto Parts, et al, will do a quick and very general code read from your OBC.

It will usually be a general code 4 digit number.

Get the code(s) and come back here: the code mavens will help.

Also, any good BMW oriented Indie repair shop can read your code, and many will have reader/software and submenus that can pinpoint fault.

Just because it 'went away', doesn't mean things are OK, unless it was something as simple as a gas cap improperly screwed on.
GL, mD

Thanks! Will do

:iagree:
If it's an OBD II code most auto supply store such as Pep Girls, Manual Zone or O'Barney can read the code for FREE.
:thumbup:

Some codes go away, some do not, like everyone else said, get them codes read! lol

Well the light went off before we even got it in to be scanned but this is what came up in the scan "The cpm has determined that a misfire has occurred with low fuel" That was a OBDII.
The second didn't have OBDII on it but said Heated oxygen sensor - bank 1 sensor 2 (H02S12) sensor circuit no activity detected.
Explanation aa Air/Fuel ratio concern - lean or rich
Probable cause aa1 Open or short circuit concern
aa2 Faulty H02S12 (Bank 1 Sensor 2

I tried to attach a file with the info but was unsuccessful so the above is what was printed.
Hope this is decipherable Lol

did the light come on under a load - like going up a hill? you might have issues as simple as a bad coil/spark plug to wiring harness, to fuel filter, to fuel pump, to serious vacuum leak anywhere from air filter all the way to a crack in the engine housing...

while the above clearly eliminates the suspension and the interior lights and whatnot, it is still a list to tackle...

when engine management detects a misfire, it will evaluate the condition and if it repeats itself again, the management will kill the fuel supply to that cylinder to avoid killing the cats with unburned fuel traveling through exhaust, and possibly igniting there... periodically it will recheck the conditions of the shunt cylinder to see if it can use it, but otherwise, it will keep the cylinder out of picture... when the misfire is serious enough, it illuminates the light... the light can turn off if the original condition is gone, but the fault code will be stored in the memory until it is erased.

the light can illuminate for a few dozen reasons, from the gas cap not screwed in tightly, to complete loss of oil pressure inside the engine... that light is just to tell you to hook up a computer to read the codes...

in addition to the codes that you have read, if you connect the car to BMW specialized computer, it will give more details, along with mileage (in kms) and RPMs when the error was logged in... the specialized software is better at pinpointing to a problem as it reads info that generic code readers do not even see...

from your explanation, i would worry about the misfire as a primary issue and the "no circuit activity" as a secondary issue...

while i would recommend getting a real read-out, tell us more about the car...

does engine idle rough? when you rev it up, does it go up and down the tach smoothly, or it stumbles somewhere?

when the light came on first time, what symptoms was the car experiencing? was it shaking? was it rough? were you at a stop or were you cruising, or going up a hill or something?

tell us more about it, i am sure there are folks here that can guide you in the right direction...

The car was operating normal. Just driving not going uphill, not towing anything, nothing out of the ordinary. The engine doesn't have any issues at all. Runs fine and no hesitation or misses. The only thing abnormal is the check engine soon light being on.

did it come on right after a fill?

I don't believe so but I don't recall for sure