Bank two sensor one air/fuel ratio sensor no CEL

I have been tracking my gas mileage for over two months and have consistently been getting 17 city and 14 highway. took it to a Sparks computerized car care to hook up to a diagnostic computer. They said that bank two sensor 1 (air/fuel ratio sensor ) is not firing properly causing the truck to use more gas consumption. Weird thing is that I have no check engine light on, even the mechanic said it was weird. Has anyone else experienced this? From what I read the sensors can partially work “get lazy” and still not throw a check engine light on. Any insight is appreciated! Thanks

 

they said your sensor should be firing? do you have an app like "torque" where you can read your own codes and see what is goin on? you can monitor your fuel trims with that and if they are out of wack that would be an indicator something was up, they typically wont throw a code unless your long term fuel trim is +-10%

 

I forget the exact wording they use but somewhere along the lines of that sensor not performing 100%. So a sensor could be preforming at +-10% and not throw a code? I do not have that app but could look into it. Should I not be so sure that this is the issue?

 

so your fuel trim is how much the computer is adding or subtracting to maintain set afrs (14.7 ish for the most part in closed loop) in a perfect world that would be 0 but that never happens because of any number of factors from temp change in the intake air to humidity the amount of fuel that is burn vs unburned that is sent out the exhaust ect, so in the real world i think about +-3% is the goal. however the computer will compensate past those parameters to keep everything running safely and anything inside about 10% is not enough out of the norm to warrant a code more often than not. I would recommend at least downloading torque if you have an android and looking at some of the stuff in there to get a better idea of what is going on with your truck. It could be the sensor, or you may have an injector that is stuck, or your evap canister may be bad could be pulling in a little extra fuel when the system check tank vacuum... have you changed anything on your truck recently?

 

welcome to realization of typical tacoma gas milage..

 

Not exactly. 14 highway and 17 city is flipped indicating something is wrong . Accepting those number as Efficient engine running would be coming to that realization.

 

i apologize my sarcasm is incredibly dry.

 

Thanks for the information. I have an iPhone. Not sure if that is Compatible. I had a k&n filter but took it out and went back to oem, I cleaned my throttle body and removed my gun/recovery case from my topper. None have improved my milage numbers. That’s where I gave up and paid 100$ to plug it into a computer . When they came back with this sensor not working properly I thought I had found the issue but just thought it was weird that everyone said I should’ve had a check engine light. I want to say that they checked everything else in the fuel system And it all showed to be working properly besides the bank two sensor 1.

 

Lol you’re good just trying to figure out an issue outside of the “I have a truck and want 25 mpg” questions. I’ve came across backwards numbers and wanna figure out the issue.