My truck's gas mileage has been dropping. After investigating a number of YouTube video's I suspect the O2 sensors have become clogged with carbon. Most of the video's I've seen show spraying them with some kind of cleaner, be it "Carb Cleaner" or some other aggressive chemical. They all claim to improve gas mileage back to around factory original mileage.

NO, I'M NOT LOOKING FOR SOMETHING TO GIVE ME 100 MPG. Just tired of seeing 15 to 16 MPG on a vehicle that used to get (at best) 25 MPG (Typical highway 22 MPG, city 19 MPG).

Gasoline producers run two grades of fuel. One formula is meant for winter driving. Less polluting but also reduced mileage. Even then, 18 MPG city was something I'd normally see. As of this year mileage has been dropping like a fly. I could replace the "UpStream" sensors at a cost of around $200 each. For a couple 10 spots I can get an ultrasonic cleaner. HOWEVER, I don't want to destroy the sensors either. So if anyone has experience or advice - please chime in.

 

Many years ago I worked as a Microsection Technician. One function of my job was to prepare samples for mounting and examination. Prior to mounting they had to be cleaned. A UC (Ultrasonic Cleaner) was used to bust loose dirt from the sample board. An inspector asked me if my UC would clean her inspection stamps. I said "Let's try it." When I held the stamp suspended in the water I found a sweet spot where the sound waves were focused and would bust the ink and other accumulated junk out of the stamp. Later I stuck my finger in the water. At various depths I didn't feel much going on. But at a specific location in the tank I felt significant pain. The sound waves were focused on the bone in the tip of my finger. Hurt but wasn't harmful. I suppose if I left my finger there I could have bruised the bone. Maybe. IDK!

The UC was a cheap one. Turn it on, dunk parts, turn it off. Nearly all of the ones I'm seeing on Amazon have electronic timers. No, I'm not asking for which UC is best, just want some feedback on the idea of using UC sound waves to bust carbon off and out of the sensors. If it works it could save me over $400. So spending a tenth of that doesn't sound like a bad investment.

 

O2-Sensors become permanently contaminated by
various Gasoline-Additives and are not "cleanable".

If You pay more than ~$50 bucks for an O2-Sensor, you're either
being ripped-off, or You have an odd Car with a "special" Sensor.

If You have a Car less than ~10-years old, You probably have
a much more serious problem than just a worn-out O2-Sensor.
Most will go well over ~100,000 miles before needing replacement.
The need for a replacement is usually indicated by a slow response-time.
Usually, the Engine-Computer will "throw a Code" when the O2 needs replacement.
.
.
.

 

If You pay more than ~$50 bucks for an O2-Sensor, you're either
being ripped-off, or You have an odd Car with a "special" Sensor.

2017 Toyota Tacoma
Sensor: https://www.autozone.com/engine-management/oxygen-sensor/p/ntk-oxygen-sensor-24661/409128_0_0
And that's for just one of them.

Over the past year I've noticed a smell upon starting the truck. Has around 55K miles (will check when I go out this afternoon). Gas mileage has been dropping.

tired of seeing 15 to 16 MPG on a vehicle that used to get (at best) 25 MPG (Typical highway 22 MPG, city 19 MPG).

I'll check Rock Auto and see what their price is. But it's not an odd vehicle. At least not odd here in the USA.

 

At Rock Auto: (not the Downstream, Upstream Right or Left (or both)) $90.79. Parts are not cheap anymore. The previous listing was from Autozone.