Using a lot of fuel
5 Year Member
Joined: Sep 2016
Posts: 267
Likes: 64
Because of the way they are monitored and tested throughout the drivecyle it's sort of a drawn out process. The sensor won't show bad until it fails 3 times consecutively and that could take awhile. For this reason, they SHOULD be replaced at 100,000 miles. It's their lifespan and that's fairly accurate.
Say you were to get two fails and then a pass during monitor testing. You would be dragging out the inevitable but during this time putting up with very bad economy. It will also run like *** lol. You'll never experience the problem normally, if you swap them ALL out every 100k. Have to swap all 4 out though, not just two if you want that truck running perfectly...or as good as it can. Kind of like a advanced maintenance regimen to follow.
Running with bad O2 sensors transforms the vehicle into slow poor running slug. Your always on fuel, always sucking it. They are toast when get CEL, but are bad way before that occurs. Reason for the 100k regimen.
Say you were to get two fails and then a pass during monitor testing. You would be dragging out the inevitable but during this time putting up with very bad economy. It will also run like *** lol. You'll never experience the problem normally, if you swap them ALL out every 100k. Have to swap all 4 out though, not just two if you want that truck running perfectly...or as good as it can. Kind of like a advanced maintenance regimen to follow.
Running with bad O2 sensors transforms the vehicle into slow poor running slug. Your always on fuel, always sucking it. They are toast when get CEL, but are bad way before that occurs. Reason for the 100k regimen.
98 F150 5.4L E40D/4R100
Joined: Nov 2006
Posts: 28,529
Likes: 7,636
From: MI
No problem 
Note: A little correction to what I posted. The sensors do not need to fail 3 consecutive times to produce a DTC, I just noticed I had that a little wrong. How it actually works, the sensors are sampled 3 consecutive times. If 2 out of the 3 samples fail, THEN the PCM forwards a DTC.
Note: A little correction to what I posted. The sensors do not need to fail 3 consecutive times to produce a DTC, I just noticed I had that a little wrong. How it actually works, the sensors are sampled 3 consecutive times. If 2 out of the 3 samples fail, THEN the PCM forwards a DTC.
Thread Starter
Junior Member
Joined: Jul 2015
Posts: 19
Likes: 1
From: Mesa AZ.
I burned off the fuel and filled with 91 from my regular top tier fuel station and started
to document fuel mileage. After 2nd fill up I ended up with 14.2 average, the driving
was a mix of moderate traffic, rush hour, freeway and few heavy footed moments.
After about the 1rst half tank it started running like normal again.
I believe this was the result of a bad tank of fuel. With a tune I believe that it will be more sensitive and my tuner did tell me to always try and use the same gas station!
This was the first thing I tried and did not want to start making changes like pulling
the chip or changing 02's and stuff like that, one thing at a time!
I was afraid there, that my truck was not going to make the 300k club, being only a oil change away!
Thank You!
to document fuel mileage. After 2nd fill up I ended up with 14.2 average, the driving
was a mix of moderate traffic, rush hour, freeway and few heavy footed moments.
After about the 1rst half tank it started running like normal again.
I believe this was the result of a bad tank of fuel. With a tune I believe that it will be more sensitive and my tuner did tell me to always try and use the same gas station!
This was the first thing I tried and did not want to start making changes like pulling
the chip or changing 02's and stuff like that, one thing at a time!
I was afraid there, that my truck was not going to make the 300k club, being only a oil change away!
Thank You!
I burned off the fuel and filled with 91 from my regular top tier fuel station and started
to document fuel mileage. After 2nd fill up I ended up with 14.2 average, the driving
was a mix of moderate traffic, rush hour, freeway and few heavy footed moments.
After about the 1rst half tank it started running like normal again.
I believe this was the result of a bad tank of fuel. With a tune I believe that it will be more sensitive and my tuner did tell me to always try and use the same gas station!
This was the first thing I tried and did not want to start making changes like pulling
the chip or changing 02's and stuff like that, one thing at a time!
I was afraid there, that my truck was not going to make the 300k club, being only a oil change away!
Thank You!
to document fuel mileage. After 2nd fill up I ended up with 14.2 average, the driving
was a mix of moderate traffic, rush hour, freeway and few heavy footed moments.
After about the 1rst half tank it started running like normal again.
I believe this was the result of a bad tank of fuel. With a tune I believe that it will be more sensitive and my tuner did tell me to always try and use the same gas station!
This was the first thing I tried and did not want to start making changes like pulling
the chip or changing 02's and stuff like that, one thing at a time!
I was afraid there, that my truck was not going to make the 300k club, being only a oil change away!
Thank You!