Questions and Answers

Toyota 4 Runner Smells Like Sulfur Q. The son has a 1997 Toyota 4 Runner, V-6 automatic transmission and over 100,000 miles. With the tailgate window down, he gets a whiff of exhaust fumes when he pulls up to a stoplight. Over the last several months he's noticed that the fumes are smelling more and more like "sulfur". Also during this time period, he has changed from a high octane fuel to a lower octane. Any thoughts or advice would be greatly appreciated. Thank you, Kathy

A. Most times that "rotten egg" smell is caused by the type of fuel is used. Cheaper fuel, which is not as pure as a premium fuel, will have more impurities that can cause that smell. So it may very well be the change in fuel is the primary cause of the smell.

In addition an excessively rich fuel mixture could cause the smell. I would let a Toyota Dealer check it for codes with their scan tool and check the EFI system in general. If it all checks out, then he will either live with the smell or use the better grade of fuel.