Is there any way to tell if O2 Sensors are worn? (1 Viewer)

[NoTempoLimit]

My 2006 LC has just under 124 miles. I believe the O2 sensors are original. I have service records and there is no record of them being changed. I've got no MIL light or codes.

I believe my fuel economy is sub-par, I'm getting below 12 mpg in city driving with some freeway driving mixed in (based on trip computer). My LC has the 5-speed and VVTi, shouldn't it be able to reach at least 13 mpg in mixed driving?

My tires are larger diameter than stock (275/70-18) and I'm factoring that in (IOW, I know the MPG is reading 7% low). I've not been able to do a mileage/gallons test yet.

I'm about to set out on a very long highway trip with a full load, so a small investment in maintenance could bring significant savings in fuel on that trip. But I don't want to just throw parts at the truck.

Air filter and spark plugs are new, so one possibility would be aged O2 sensors.

I had the experience last year with my 2000 BMW E46 (18 years old and about 100k miles) where I was getting no trouble codes, and engine was running smoothly, but it wouldn't clear the emissions monitors to pass Smog. I found out about "lazy" O2 sensors, changed mine out and the monitors cleared right away and it passed. Fuel economy also increased slightly.

Let me know what you guys think...

 

[nukegoat]

You can use an OBD 2 tool to plot the voltages of the pre-cat and post-cat sensors and look at the long term fuel trim in the computer. There are 4 sensors, and the computer will be relatively finicky if they're inconsistent with one another. Read up on how to diagnose with those things.

12mpg for mixed driving sadly seems about normal to me, for what it's worth.

 

[Matthew Hindle]

When my upstream sensors were on their way out i had two symptoms. Terrible mpg and the smell of my cats burning as they were getting too hot

 

[NoTempoLimit]

When my upstream sensors were on their way out i had two symptoms. Terrible mpg and the smell of my cats burning as they were getting too hot

WOW OK, at what mileage did that happen? Overheating cats are not good. My first car was a first generation Mazda RX-7. I've seen a cat glow orange-yellow. Doesn't give you the warm fuzzies...

 

[Matthew Hindle]

So it happened about six months ago my truck has only done 120,000!!
My cats did survive I haven’t had to replace them yet my truck still passes emissions.
Since changing the sensors i average 16-18 mpg so happy with that! Usual 33 tires, bumper, sliders etc etc.
Your first car was a mazda rx-7?! Someone’s doing well! Mine was a one litre mini ha ha