I have a 1995 Lexus LS 400. I have always used premium gas in it. I just recently decided to use the 89 Octane gas for it. The next day after using 89 Octane gas, my check engine light came on. Does any one know why?, Can 89 Octane gas cause this problem since it happened as soon as I used 89?. If I use premium again, will that clean my system and make the check engine light go away?. thanks

 

First and foremost,, I would determine what the CEL code is. You can stop by your local auoparts store, in most cases, and have them scan the code since yours is OBDII. Most of the time they do not charge for that service. The difference in gas COULD cause the CEL to pop up,most likely due to the knock sensors being "confused" by the lower octane gas. Once you have a code pop up, it will have to be manually cleared by a code reader machine OR you can unplug the positive on the batery for a few and then re-hook. This will clear is out.

Shouldn't be that big of a problem with using the 89, I do so myself, and have done so for awhile now without problem. Just make sure you know what the CEL is telling you before you have it cleared out.

 

bet they didnt click 3 times lol

sorry couldnt resist.

 

Also check your gas cap. If its broken or not tighten down all the way the check engine light will go on also.