Loss of MPG

[RETRO]

I know these post come up often. I have a 2008 Yaris HB. I bought used 5 years ago with 24k miles. For 4 years I got 41-42 mpg in the summer and 39-40 mpg in the wither. Dec 2013 I noticed my mpg dropping.I lost about 2 mpg per tank.I have changed the plugs that made no difference. Today I am getting 33 mpg in the winter and 36 in the summer. I use the same station for years. I now am using another station and getting the same about 32-33 mpg.My driving is the same and nothing has changed on it. really confused on this car runs smooth just not sure what else to do.Suggestions Thanks.

[Bluevitz-rs]

It's possible the AFR sensor is getting lazy. My '05 was getting the same way except i was getting random codes regarding running too lean and misfires. So I had a friend perform an active test on the cars fuel enrichment while monitoring the O2 reading and it indicated the sensor was not reading properly anymore. Replaced it and gained 100-150km per tank.

Might be something to concider.

It might also be that the fuel companies are adding more and more ethanol content to the fuel mix.

[Astroman]

This was posted in the wrong section of the forum, moved it to the correct one. :smoking:

[RETRO]

I've clean the MAF,throttle body. Ran seafoam through the brake booster and tank. Still no improvement.Thats my thinking higher % of ethanol in gas.

[Bluevitz-rs]

Have you monitored the A/F sensor to make certain it's reading correctly?

[RETRO]

Have you monitored the A/F sensor to make certain it's reading correctly?

I have not and not sure how to.

[Bluevitz-rs]

You'll need a wiring diagram. You might be able to back probe the OBD connector inside the car with a volt meter to take the reading while you drive the car.

CTScott might be able to help.

[RETRO]

it is reading 0.2 volts at idle? what is the correct voltage?