My Ford Ranger has been getting worse and worse fuel economy recently. Last time I calculated it was getting 11 MPG. The truck isn't down on power or anything either. It might just be me thinking things but if anything it seems to have more power than ever. I first started noticing it after I had to unplug the battery to run a new starter solenoid signal wire from the relay. I also have replaced the radiator recently too. It use to get around 200 miles on the trip meter before I'd fill it up when it reached a quarter of a tank left but now it only really gets around 150 miles or so. I was wondering what I could look at to try and resolve the fuel economy issues. Any help would be appreciated.

 

First thing is to changes the O2 sensors
These are the only sensors that wear out
12 years or 100k miles
After that MPG starts to drop, but very slowly

O2s generate their own voltage, 0.1v to 0.9v
0.1v is "lean"
0.9v is "rich"

As O2s age they can't generate voltage as well, so your computer "sees" that as lean, so adds more fuel than needed, because its a "false lean", like an air leak
MPG suffers
They will not set codes because they are "technically working", just not working well, lol

 

So how would I go about checking those? Also are O2 sensors the ones on the exhaust?

 

You don't check them you replace them
2001 vehicle is 21 years old, so at minimum it should be close to End Of Life for 2nd set of O2s, 24 years
If over 200k miles then for sure, should be getting 3rd set

Yes, on the exhaust system
On 4cyl engine there are 2
In V6 engines there are 3 sometimes 4

Wrench size is 22mm or 7/8"

 

Do they use "Winter Blend" gasoline where you live ?

Most states do from October to May,

 

No they don't use winter blend gasoline.

 

I would like to make sure that the part I'm replacing is bad and the cause before I load the parts cannon and spend 200 bucks on sensors.

 

Do a search here as I have posted about the O2 sensors I replaced with Bosch, listing the part numbers and they were a direct fit. They are not $200, and not very expensive compared how much fuel you're wasting.

 

Where do you get them from? On O'Reilly's website the Bosch ones are like 60 bucks each and my truck has 3. 2 upstream and 1 downstream.

 

Rock Auto will probably have the best price. Good selection. Bosche, Denso, Motorcraft are good brands. Bosche should be less than $25 each and add a little for shipping.

Start soaking the O2 sensor flanges with penetrating oil (daily). Use the proper wrench with leverage. Wear gloves. Try and not use the Lord's name in vain. :)

Oh, and make sure your tires are properly inflated.

 

Here is the write up I did back in 2021 about them and included the part numbers for the Bosch parts you need. Armed with the part number that i sourced from Bosch directly online I then took the part numbers and started shopping for the best price.

I thought I would post this here as I had to replace my downstream sensor (the one after the catalytic converter) because I had a DTC code for it. I used a Bosch Exact Fit (per the Bosch website) for my 2003 Ranger 3.0 Automatic for the one after the CAT (Downstream). While I had the inner fender wells out I realized I can access the sensors very easily and after 244K miles on the original ones I decided to change those also. These are the 2 before the CAT (Upstream).

Here are the part numbers:
O2 Sensor Downstream - Bosch part number 15716, you only need one.
O2 Sensors Upstream - Bosch part number 15664, you will need 2.
One for each side of the engine, they are located right after the exhaust manifold (there is one on the driver's side and one on the passenger side (bank 1 and bank 2).
I hope this helps.

Good Luck! Let us know how we can help you further.