Throttle sensor & losing gas milage


Could you tell me if using up a lot of gas has anything to do with a throttle sensor not working. They told me it was the throtle sensor?

It very well may. Do you have a reason to be suspect of their diagnosis?

Well it may, or a lot of other things.

Maybe if you filled us in on why you are asking the question we might be able to offer some useful advice. :slight_smile:

No, I trust that its my throttle sensor I just don’t know what it does? Does it eat up the gas or tell the engine to use more gas. My own mechanic at first told me not to bother with it because it wasn’t worth replacing it that something inside probably got stuck… My car is a 1997 Subru legacy and I have noticed I have to fill it up more often

A throttle position sensor (tps) tells the engine computer that you have pressed, released, or held steady, the gas pedal. A bad tps can make the car jerk, or lag, when you press, or release, the gas pedal. I don’t think it would affect gas mileage that much. There are other sensors that could. If the check engine light is on, Auto Zone, and other auto parts stores, will read the light, for free. If you do that, and get a trouble code, bring it here for advice.

Usually it’s the cold weather causing loss of gas mileage or the crummy winter gasoline formula. The fuel injectors can get dirty or plain worn out. There are lots of things that can effect mileage. Even low tire pressure or misalignment.

Get another mechanic. The TPS sensor should be an easy replacement, and the computer uses this and other sensors to determine the proper fuel rate to meter into the engine. A bad TPS sensor or other sensor will affect gas mileage, just in different ways, determined by how the computer’s programming uses the sensors. But, THEY ARE ALL IMPORTANT FOR A SMOOTH RUNNING ENGINE. I found a couple of on-line sites that have this sensor for $60.00, so it is not really expensive. And, it is usually mounted right on the throttle body, where it is easy to get to.

Hi Busted knuckles!
Thank you all for your replys…I found them very helpfull. I was wondering if you could tell me the online sites that may have the part for this I would be very grateful…Cindy

Here is,carcode,1269996,parttype,5136,partGroup,19

Here is,2353202/initialAction,partTypeResultSet/initialN,15900136/shopping/vehicleSelected.htm

This part looks like it is adjustable, so installation will also require a calibrated adjustment. Typically, this is done with a handheld ODB-II scan tool and a chart with the correct reference voltage for the TPS at rest. But, it still should be a quick and easy replacement. With my scan tool, I can change one out and calibrate it in less than 30 min.

Even if it is the throttle sensor, it may not be bad-- just need adjustment. Heck, my car’s way older than 1997, and the original TPS still works fine. Ya may want a competent mechanic to perform a sweep test (easy test w/ a voltmeter) on it before you spend $75+ on a new one.

Thank you so much! I checked out both sites and I think I will go with Autozone. I wish you were in my area cause I would take my car to you… Do you know where I could find a competent mechanic? MY zip code is 03307. I was thinking about taking it to the dealer here in Concord,NH but I don’t think they would let me buy the part somewhere else!! Thanks, Cindy

Hi VelocityBoy,
I had my mechanic put it on a computer and then I had this guy at Midis muffler check it with a hand held thing that he plugged in I think to check it so I think that was a voltage meter. Anyway when I find a good mechanic I will have him do what you said a sweep test to make sure. thanks,Cindy

The check engine light has been scanned once, maybe twice. You haven’t told us if the check engine light ever came on; nor, if the scan(s) showed a trouble code. Did it, and was there a trouble code? An engine tune-up affects gas usage. Has it had a recent tune-up (changing spark plugs, maybe wires, air filter, pcv valve, etc.) ? //// To find a mechanic/shop recommended by customers, go to the bottom of this page, and click on Actual Car Info. On the new page, scroll down to Owning? and click on Mechanics File. Put your zip code in, and the distance you’re willing to travel. Read the reviews, and choose a shop.

The check engine light would come on for sometimes a couple of weeks and then it would go off for a few days and then stay on again. They did come up with a code can’t remember now. It hasn’t had a tune up in 2 years. I am planning to do that soon after I fix the throttle sensor. Thank you so much for the info on finding a mechanic I am going to go do that now so again thank you!

For your mechanic, make notes of all the symptoms of the ways the engine is performing differently than when it was healthy. // The check engine light trouble code may have been P0505 - P0509 “idle air control system”. Any mechanic will scan it, again. The scan yields information from ALL the sensors about what is going on in the engine, emissions wise.