Could Low octane gas cause Check Engine Light?

[scaldes]

I'll try to make this short (whilst lessening the appearance of me being an idiot). I just bought an A4 (2.8 Quattro) in San Diego (love the car so far) and drove it back here to Las Cruces, NM. In san Diego, the lowest octane gas is 87 (which, the manual says, is okay). But here, in Nowheres-ville, the low is 86. And two days ago, without looking (I'm a graduate student with not a whole lot of dough) i just put in the cheepest stuff (which was 86). No more than twenty miles later, my Check Engine Light went on. Could it be a coincidence (sp.), sure. But since that check engine light is linked , pretty much, to emissions control, that would make sense. Does anyone know for sure?
Any help would be much appreciated. Thanks.

[Talibangunner925]

I dont think it would make it go on for shure but it could clog up you fuel injectors eventually and in the manual at least in minge it says to run 93 octain

[MikeLee2484]

yeha if your manual tells you to put a certain octane gas in it you should put that grade of octane in...though you are student you can afford the higher octane...plus it will be better for the wallet in the end if you have to pay for major repairs

[lodownlv]

yes yes yes run 91 or higher

[Talibangunner925]

a new study in euro tuner said that the diffrence between midgrade and high test are very samll....at one time i was running low octanine...wow after 3 weeks of running it my engine (with low octaine) started to bog out some times...so i put in high test in fear of my car and some injector clenaer and fixed the problem.... after another week i put in mid grade and have been puting it in ever since and hanvent had any problems what so ever

[ctesla]

will it cause damage; possibly, but this is an EXTENDED amount of fill-ups, and MANY miles, then an O2 or cat could be damaged.
will it pop the check engine light; definitely. if a check eng. light will light up for something as insignificant as your fuel cap being loose, you can be certain she'll light up for this.
will it hurt; not really, if you feel engine "ping", then you should jump to the next higher octane, or run an octane boost, or 3-4ounces of Acetone through, every now and again.

my Audi's were spoiled, and only got 100 Octane Lo-Lead, from the race pits, and now, they get an ocassional tank of Premium (93), but have been getting 86oct ever since Shell decided they needed $3./gal for the good stuff. my light comes on, and as a certified technician, I know exactly how to correct this:
black electrical tape over the light; light goes away.
honestly, even on '05 and '06s, the light is mainly a feedback for emissions, not maintenance. if you have a "flashing" engine light, this is something CRITICAL, and should be taken care of immediately, but otherwise; drive on, unless a driveability issue appears.
but I can definitely tell the difference from 100 to 93 to 86; of course in stop and go, we don't see many 140+mph runs.

anyhow, if you have switched back to Premium, light should go off, after a couple of drive cycles (30-50miles); however, if not, it maybe related to another emission item, or a lean/rich condition in the injectors (which the Audi computer will compensate for, and you shouldn't notice), which will correct with a higher octane, or possibly a computer reset.
hope this helps,
chris
nrt racing

[veedubmechanic]

Cali has different emissions regulations than NM does. They have there own special one that no other state has. There check lights will most likely come on more due to the more strict emissions limits that the computer has. Using crappy low grade fuel in the middle of knowhere will most likely cause engine misfires and a check light. I have always used 92/93 octane in my cars and have never had issues with performance or drivability. Every so often I put in a tank of 87 octane and I notice a huge difference in vibrations at idle, cranking time, and performance. Thats why I always stick with the extra 2-3.00 extra per tank fill up of 93 octane.

9gallons at 2.79/gallon 87octane = 25.11
9gallons at 3.00/gallon 93octane = 27.00

Its sad people think that its sooooooooooo much more to put in premium.
Now if you had a gas guzzler suv that has a 25gallon tank then i would see why you wouldnt wanna spend the extra money for 93octane.

[lodownlv]

i can tell and yes it dose make a diffrence in milage from the computer on my 99 passat turbo 1.8

[Audi4life]

Hello,

I have created an account here just to tell you that "Yes it can". I know a few other posters will bring theoretical knowledge, but I have practical experience.

I have make the mistake of putting regular/low octane gas (87), on my 2004 Audi A4, and within 50 miles of driving the check engine light came on.

The first time I did it by accident, and the second time I did it on purpose.

In conclusion, if you wanted to know if low octane gas could cause the check engine light to come on, I can truthfully tell you that "yes", because I have seen it. Please stick to 91 upwards.

[mcgeeca]

This is great news. I recently have had the same problem. I have a 2002 VW Passat Wagon 1.8 L. Without thinking, I have been putting the mid-grade (89) gas in the car for the past 2 or 3 fill ups. This past fill, I drove for about 30 miles and then noticed the check engine like on. This was also right after I replaced my headlight bulbs. (I was thinking to myself, how the heck could replacing headlight bulbs make my engine light come on)

After noticing the engine light, I was at half a tank. I stopped at shell immediately and filled the rest of the tank up with 92 octane premium gas, hoping this would solve the issue. I have only driven about 5 miles after the refill and the light is still on. I know that I must drive a little while longer for it to make a difference, but hopefully soon, the light will turn off.

Audi's and VW's are pretty much brother and sister. Most often, the issues that they have are common in both brands.

-mcgeeca