Hello,

I've got a stock 03 4Runner v6 4WD. After a trip to yosemite last year in the winter my front 02 (california spec) sensor went out. The dealer changed it out for me. Ever since then I can smell the fumes coming out the exhaust and my MPG has dropped by 6-8 MPG. I bought a OBD II reader and everything seems in line ? I changed out the spark plugs and the air filter and the same thing?

Any advice ?
Thanks
Rany

 

What kind of fumes? Is it your typical exhaust smell only stronger, or a fuel or sulfur smell?

 

that would cause a smell and decrease your gas mileage.

 

How do you tell if your cat is bad?

 

Catalytic converters are usually covered as part of the emissions system which follows a longer warranty period, 7/70 usually.

The fact that they 02 sensor was replaced because it was giving bad readings leads me to believe you have a bad cat. Was it the pre-02 or post-02. Usually there is an 02 sensor before and after the cat.

 

Seems like the emissions warranty is something like 8 years 84,000 miles. I'm not totally sure of the exact years/miles, but I do know that it's the same coverage period for every vehicle and that it's federally mandated. As a matter of fact, I think that the O2 sensors are covered under the emissions warranty, so you shouldn't have had to pay for it the first time.

I would check into it.