Questions and Answers

Toyota Avalon CEL On Q. Vincent, I have a 1998 Toyota Avalon XLS, with V-6 and 42,000 miles. I recently had the Check Engine Light come on while driving. No noticeable change in drivability (i.e., engine idled and accelerated smoothly). The two things that I did that were out of the norm before the light came on was:

1) drive in very rainy and muddy conditions.

2) fill the tank with 83 octane (I usually fill it up with 93).

I took it to a local service station but the technician was not in that day and the owner suggested it might be bad gas. After consulting my owner's manual it turned out that 87 was the minimum suggested octane.

Before spending $80.00 for a diagnostic, and assuming the low octane is the problem, do you think it is worthwhile to fill the tank with 87 octane in the hopes of cleansing the system and therefore causing the check engine light to go out?

Thanks in advance.

A. Low octane fuel will not turn the CEL on. There maybe a fuel related problem, but you won't know for sure until you pull the codes. An AutoZone or NAPA auto parts store will scan the system and get the codes for free. Once we know what the codes are, we'll know what we're dealing with.