Gas Mileage Dropping

I recently relocated to Iowa from Alabama in my 2001 2.7L Tacoma X-Cab. My engine light has never been on since I bought the truck new in August 2001. Three weeks after i arrived in Iowa my engine light came on and has not gone off. I just rolled over 220K on this truck and I have never had any major issues with it. My gas mileage was 25 mpg and as of yesterday has dropped to just above 18 mpg. Any Ideas?

 

Have Autozone or someone read the codes for the check engine light (free service). It'll let you know what your engine is thinking. Would be a good place to start.

 

I did and the codes were P1135 and P1130.

 

Sounds like an A/F sensor, which is your upstream sensor. Gas mileage also gets slightly worse this time of year because of the winter gasoline mix.

 

Been driving this truck for 12 years through all four seasons, hot, cold, and everthing else. The engine light has never been on before and my gas mileage has always been between 24 and 26 mpg.

 

Pretty sure Alabama doesn't use winter gas mixes because you don't get many cold front/heavy air masses in the region.

I'm not a meteorologist, so I could be wrong.

 

That makes sense, I will check it out. Thanks for the advice.

 

Sell the truck and get a Prius.

 

If you're AF sensor is bad it'll cause your MPG to suffer.

 

I assumed since he said he moved to Iowa, they used winter gas blend there.

 

Yeah, I responded to him to inform him that Iowa is probably different than Alabama.

 

From another thread:

You are probably better off replacing the A/F sensor. Winter gas shouldn't cause the check engine light to come on. If you want to buy the part online, look for an "upstream" sensor. Lowest-cost part on RockAuto is NTK Part # 24669 for $130.

 

How difficult is it to replace the A/F sensor?

 

Iowa uses high ethanol fuel, which will make your fuel mileage drop also...

Corn is meant for human, and animal consumption... Not for our trucks...

 

Most difficult part tends to be unplugging the electrical connector. Then you just unscrew the sensor from the exhaust pipe with a box wrench:

http://www.4x4wire.com/toyota/4Runner/tech/O2_Sensor/