740i check engine light reset

[Marz740il]

Picked up the 740i today just outside of Indianapolis which is about 3 hours away from me. Drove it back about 190miles ran perfect, amazing no warning lights or anything. Before we left Indy to come home my Dad put 87 octane gas in it which I forgot to tell him nothing but 89 octane. After the drive home I was driving a friend to the airport and the check engine light came on. I was wondering if it was caused by lowering the octane down in Indy. When I got home I changed the oil, and went and filled up with 89 octane. I wanted to reset the check engine light to see if it goes off, does anyone know how to do this also, if it is even possible for the octane change to set off the check engine light.

Thanks,
Mike

[dhapp]

you can get and OBD II auto scanner (I have an actron CP9135 which works great) at an auto part store for about $100 which can read the code and reset Good Luck.

[lincolnmaster80]

You can go cheaper a route. You can use a piece of wire to jump the pins in the OBD port...however, getting an OBD tool can and will save you money later down the road. However, there is a reason why the check engine light comes on and the OBD tool from Peake is a good idea. I'll try to find the pin reset method as I couldn't find where I seen it.

Apparently, you can also disconnect the battery cables, connect both cables together and turn on your hazard lights while battery is disconnected so that any residual electricity is used. This would drain all memory and might reset your computer and error codes. If the engine light goes off after this, but comes on after a while, there is a problem you should look into. Autozone will do a free scan and reset for free as well.

The octane MIGHT have an effect, but I've never heard of any instant or immediate problems occuring. However, after a long period of time, this may have some serious draw backs, as the car was designed to be used on 91 octane or above. The BMW manual recommends 91 octane, just so you know. Not only will your engine run better, but you will most lightly get better fuel milage. If you go farther on less fuel, you're really breaking even, if not doing better than you would putting more fuel in and having to fill up more offen with the money you save. Not trying to pressure you into filling up with 91, but it could save you a lot of money in the future. Even with the compression ratio the way it is, it theoretically can run on lower, but it was designed for 91 in mind...

Also, if there is a problem and the check engine light is still on, it takes about three restarts for the computer to make sure that the problem is gone.

[ray mckinney]

auto zone cannot check certain years so you may want to call and ask first.

[lincolnmaster80]

Couldn't find the pin reset method for the check engine light...I might have been thinking about the oil service reset method...

[Marz740il]

Thanks, for the replys its an Fuel Trim Malfunction (Bank 1 and Bank 2). Posted another thread to see what to replace to try and get rid of it.

[clemkadiddlehopper]

Lincoln, heres a link for resetting the oil and inspection lights. I don't know of a check enginer reset except using the ODBII unit.
There may be one. Bu t I don know it.

http://www.bimmerboard.com/forums/posts/1591

BTW, check out e38.org there is a lot of good info there.

Cheers!